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Merge pull request #4 from kvedala/document/search

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Document `search` folder
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Krishna Vedala 2020-05-28 21:51:19 -04:00 committed by GitHub
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2
DIRECTORY.md
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@ -177,8 +177,8 @@
* [Jump Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/jump_search.cpp) * [Jump Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/jump_search.cpp)
* [Linear Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/linear_search.cpp) * [Linear Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/linear_search.cpp)
* [Median Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/median_search.cpp) * [Median Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/median_search.cpp)
* [Searching](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/searching.cpp)
* [Ternary Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/ternary_search.cpp) * [Ternary Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/ternary_search.cpp)
* [Text Search](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/search/text_search.cpp)
## Sorting ## Sorting
* [Bead Sort](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/sorting/bead_sort.cpp) * [Bead Sort](https://github.com/TheAlgorithms/C-Plus-Plus/blob/master/sorting/bead_sort.cpp)

28
search/binary_search.cpp
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@ -1,6 +1,20 @@
/**
* @file
* @brief [Binary search
* algorithm](https://en.wikipedia.org/wiki/Binary_search_algorithm)
*/
#include <iostream> #include <iostream>
// binary_search function
int binary_search(int a[], int l, int r, int key) { /** binary_search function
* \param [in] a array to sort
* \param [in] r right hand limit = \f$n-1\f$
* \param [in] key value to find
* \returns index if T is found
* \return -1 if T is not found
*/
int binary_search(int a[], int r, int key) {
int l = 0;
while (l <= r) { while (l <= r) {
int m = l + (r - l) / 2; int m = l + (r - l) / 2;
if (key == a[m]) if (key == a[m])
@ -12,23 +26,31 @@ int binary_search(int a[], int l, int r, int key) {
} }
return -1; return -1;
} }
/** main function */
int main(int argc, char const* argv[]) { int main(int argc, char const* argv[]) {
int n, key; int n, key;
std::cout << "Enter size of array: "; std::cout << "Enter size of array: ";
std::cin >> n; std::cin >> n;
std::cout << "Enter array elements: "; std::cout << "Enter array elements: ";
int* a = new int[n]; int* a = new int[n];
// this loop use for store value in Array // this loop use for store value in Array
for (int i = 0; i < n; i++) { for (int i = 0; i < n; i++) {
std::cin >> a[i]; std::cin >> a[i];
} }
std::cout << "Enter search key: "; std::cout << "Enter search key: ";
std::cin >> key; std::cin >> key;
// this is use for find value in given array // this is use for find value in given array
int res = binary_search(a, 0, n - 1, key); int res = binary_search(a, n - 1, key);
if (res != -1) if (res != -1)
std::cout << key << " found at index " << res << std::endl; std::cout << key << " found at index " << res << std::endl;
else else
std::cout << key << " not found" << std::endl; std::cout << key << " not found" << std::endl;
delete[] a;
return 0; return 0;
} }

63
search/exponential_search.cpp
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@ -1,20 +1,42 @@
// Copyright 2020 Divide-et-impera-11 /**
* \file
* \brief [Exponential search
* algorithm](https://en.wikipedia.org/wiki/Exponential_search)
* \copyright 2020 Divide-et-impera-11
*
* The algorithm try to search the range where the key should be.
* If it has been found we do a binary search there.
* The range of the search grows by exponential every time.
* If the key is larger than the last element of array, the start of
* block(block_front) will be equal to the end of block(block_size) and the
* algorithm return null ponter, every other cases the algoritm return fom the
* loop.
*/
#include <cassert> #include <cassert>
#include <cmath> #include <cmath>
#include <iostream> #include <iostream>
#include <string> #ifdef _MSC_VER
#include <string> // use for MS Visual C++
#else
#include <cstring> // for all other compilers
#endif
// Binary Search Algorithm(use by struzik algorithm) /** Binary Search Algorithm (used by ::struzik_search)\n
// Time Complexity O(log n) where 'n' is the number of elements * * Time Complexity O(log n) where 'n' is the number of elements
// Worst Time Complexity O(log n) * * Worst Time Complexity O(log n)
// Best Time Complexity Ω(1) * * Best Time Complexity Ω(1)
// Space Complexity O(1) * * Space Complexity O(1)
// Auxiliary Space Complexity O(1) * * Auxiliary Space Complexity O(1)
* \returns pointer to value in the array
* \returns `nullptr` if value not found
*/
template <class Type> template <class Type>
inline Type* binary_s(Type* array, size_t size, Type key) { inline Type* binary_s(Type* array, size_t size, Type key) {
int32_t lower_index(0), upper_index(size - 1), middle_index; int32_t lower_index(0), upper_index(size - 1), middle_index;
while (lower_index <= upper_index) { while (lower_index <= upper_index) {
middle_index = std::floor((lower_index + upper_index) / 2); middle_index = std::floor((lower_index + upper_index) / 2);
if (*(array + middle_index) < key) if (*(array + middle_index) < key)
lower_index = (middle_index + 1); lower_index = (middle_index + 1);
else if (*(array + middle_index) > key) else if (*(array + middle_index) > key)
@ -22,21 +44,17 @@ inline Type* binary_s(Type* array, size_t size, Type key) {
else else
return (array + middle_index); return (array + middle_index);
} }
return nullptr; return nullptr;
} }
// Struzik Search Algorithm(Exponential)
// Time Complexity O(log i)where i is the position of search key in the list /** Struzik Search Algorithm(Exponential)
// Worst Time Complexity O(log i) * * Time Complexity O(log i) where i is the position of search key in the list
// Best Time Complexity Ω(1) * * Worst Time Complexity O(log i)
// Space Complexity O(1) * * Best Time Complexity Ω(1)
// Auxiliary Space Complexity O(1) * * Space Complexity O(1)
/* Tha algorithm try to search the range where the key should be. * * Auxiliary Space Complexity O(1)
If it has been found we do a binary search there. */
The range of the search grows by exponential every time.
If the key is larger than the last element of array,
the start of block(block_front) will be equal to the end of block(block_size)
and the algorithm return null ponter,
every other cases the algoritm return fom the loop. */
template <class Type> template <class Type>
Type* struzik_search(Type* array, size_t size, Type key) { Type* struzik_search(Type* array, size_t size, Type key) {
uint32_t block_front(0), block_size = size == 0 ? 0 : 1; uint32_t block_front(0), block_size = size == 0 ? 0 : 1;
@ -51,6 +69,8 @@ Type* struzik_search(Type* array, size_t size, Type key) {
} }
return nullptr; return nullptr;
} }
/** Main function */
int main() { int main() {
// TEST CASES // TEST CASES
int* sorted_array = new int[7]{7, 10, 15, 23, 70, 105, 203}; int* sorted_array = new int[7]{7, 10, 15, 23, 70, 105, 203};
@ -59,5 +79,6 @@ int main() {
assert(struzik_search<int>(sorted_array, 7, 50) == nullptr); assert(struzik_search<int>(sorted_array, 7, 50) == nullptr);
assert(struzik_search<int>(sorted_array, 7, 7) == sorted_array); assert(struzik_search<int>(sorted_array, 7, 7) == sorted_array);
// TEST CASES // TEST CASES
delete[] sorted_array;
return 0; return 0;
} }

131
search/hash_search.cpp
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@ -1,32 +1,57 @@
// Copyright 2020 Arctic2333
#include <stdlib.h>
#include<stdio.h>
#define MAX 6 // Determines how much data
# define HASHMAX 5 // Determines the length of the hash table
/** /**
* Hash Search Algorithm * \file
* Best Time Complexity Ω(1) * \brief Hash Search Algorithm - Best Time Complexity Ω(1)
* In this algorithm, we use the method of division and reservation remainder to construct the hash function, *
* and use the method of chain address to solve the conflict, that is, we link a chain list after the data, * \copyright 2020 Arctic2333
* and store all the records whose keywords are synonyms in the same linear chain list. */ *
int data[MAX] = { 1, 10, 15, 5, 8, 7}; // test data * In this algorithm, we use the method of division and reservation remainder to
* construct the hash function, and use the method of chain address to solve the
* conflict, that is, we link a chain list after the data, and store all the
* records whose keywords are synonyms in the same linear chain list.
*
* @warning This program is only for educational purposes. It has serious flaws
* in implementation with regards to memory management resulting in large
* amounts of memory leaks.
* @todo fix the program for memory leaks and better structure in C++ and not C
* fashion
*/
#include <cstdlib>
#include <iostream>
#define MAX 6 ///< Determines how much data
#define HASHMAX 5 ///< Determines the length of the hash table
int data[MAX] = {1, 10, 15, 5, 8, 7}; //!< test data
/**
* a one-way linked list
*/
typedef struct list { typedef struct list {
int key; int key; //!< key value for node
struct list * next; struct list* next; //!< pointer to next link in the chain
} } node, /**< define node as one item list */
node, * link; *link; ///< pointer to nodes
node hashtab[HASHMAX];
int counter = 1; node hashtab[HASHMAX]; ///< array of nodes
/* int h(int key)
// int counter = 1;
/**
* Mode of hash detection : * Mode of hash detection :
* Division method */ * Division method
int h(int key) { * \param [in] key to hash
return key % HASHMAX; * \returns hash value for `key`
} */
/* void create_list(int key) int h(int key) { return key % HASHMAX; }
/**
* The same after the remainder will be added after the same hash header * The same after the remainder will be added after the same hash header
* To avoid conflict, zipper method is used * To avoid conflict, zipper method is used
* Insert elements into the linked list in the header */ * Insert elements into the linked list in the header
* \param [in] key key to add to list
* \warning dynamic memory allocated to `n` never gets freed.
* \todo fix memory leak
*/
void create_list(int key) { // Construct hash table void create_list(int key) { // Construct hash table
link p, n; link p, n;
int index; int index;
@ -39,62 +64,76 @@ void create_list(int key) { // Construct hash table
n->next = p; n->next = p;
hashtab[index].next = n; hashtab[index].next = n;
} else { } else {
hashtab[index].next = n; } hashtab[index].next = n;
} }
/* int hash_search(int key) }
* Input the key to be searched, and get the hash header position through the H (int key) function,
* then one-dimensional linear search. /**
* If found @return element depth and number of searches * Input the key to be searched, and get the hash header position through the H
* If not found @return -1 */ * (int key) function, then one-dimensional linear search. If found @return
int hash_search(int key) { // Hash lookup function * element depth and number of searches If not found @return -1
*/
int hash_search(int key, int* counter) { // Hash lookup function
link pointer; link pointer;
int index; int index;
counter = 0;
*counter = 0;
index = h(key); index = h(key);
pointer = hashtab[index].next; pointer = hashtab[index].next;
printf("data[%d]:", index);
std::cout << "data[" << index << "]:";
while (pointer != NULL) { while (pointer != NULL) {
counter++; counter[0]++;
printf("data[%d]:", pointer -> key); std::cout << "data[" << pointer->key << "]:";
if (pointer->key == key) if (pointer->key == key)
return 1; return 1;
else else
pointer = pointer->next; pointer = pointer->next;
} }
return 0; return 0;
} }
/** main function */
int main() { int main() {
link p; link p;
int key, index, i; // Key is the value to be found int key, index, i, counter; // Key is the value to be found
index = 0; index = 0;
// You can write the input mode here // You can write the input mode here
while (index < MAX) { // Construct hash table while (index < MAX) { // Construct hash table
create_list(data[index]); create_list(data[index]);
index++; index++;
} }
for (i = 0; i < HASHMAX; i++) { // Output hash table for (i = 0; i < HASHMAX; i++) { // Output hash table
printf("hashtab [%d]", i); std::cout << "hashtab [" << i << "]\n";
printf("\n");
p = hashtab[i].next; p = hashtab[i].next;
while (p != NULL) { while (p != NULL) {
printf("please int key:"); std::cout << "please int key:";
if (p->key > 0) if (p->key > 0)
printf("[%d]", p -> key); std::cout << "[" << p->key << "]";
p = p->next; p = p->next;
} }
printf("\n"); std::cout << std::endl;
} }
while (key != -1) { while (key != -1) {
// You can write the input mode here // You can write the input mode here
// test key = 10 // test key = 10
key = 10; key = 10;
if (hash_search(key)) if (hash_search(key, &counter))
printf("search time = %d\n", counter); std::cout << "search time = " << counter << std::endl;
else else
printf("no found!\n"); std::cout << "no found!\n";
key = -1; // Exit test key = -1; // Exit test
/* The test sample is returned as: data[0]:data[5]:data[15]:data[10]:search time = 3 /* The test sample is returned as:
* The search is successful. There are 10 in this set of data */ * data[0]:data[5]:data[15]:data[10]:search time = 3 The search is
* successful. There are 10 in this set of data */
} }
return 0; return 0;
} }

43
search/interpolation_search.cpp
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@ -1,11 +1,24 @@
/**
* \file
* \brief [Interpolation
* search](https://en.wikipedia.org/wiki/Interpolation_search) algorithm
*/
#include <iostream> #include <iostream>
// function to search the value in an array using interpolation search /** function to search the value in an array using interpolation search
int search(int arr[], int value, int len) { * \param [in] arr array to search in
* \param [in] value value to search for
* \param [in] len length of array
* \returns index where the value is found
* \returns 0 if not found
*/
int interpolation_search(int arr[], int value, int len) {
int low = 0, high, mid; int low = 0, high, mid;
high = len - 1; high = len - 1;
while (arr[low] <= value && arr[high] >= value) { while (arr[low] <= value && arr[high] >= value) {
mid = (low + ((value-arr[low])*(high-low)) / (arr[high]-arr[low])); mid = (low +
((value - arr[low]) * (high - low)) / (arr[high] - arr[low]));
if (arr[mid] > value) if (arr[mid] > value)
high = mid - 1; high = mid - 1;
else if (arr[mid] < value) else if (arr[mid] < value)
@ -13,24 +26,36 @@ int search(int arr[], int value, int len) {
else else
return mid; return mid;
} }
if (arr[low] == value) if (arr[low] == value)
return low; return low;
return 0;
return -1;
} }
/** main function */
int main() { int main() {
int n, value, array[100], re; int n, value, re;
std::cout << "Enter the size of array(less than 100) : "; std::cout << "Enter the size of array(less than 100) : ";
std::cin >> n; std::cin >> n;
int *array = new int[n];
std::cout << "array in ascending (increasing) order : " << std::endl; std::cout << "array in ascending (increasing) order : " << std::endl;
for (int i=0; i < n; i++)
std::cin >> array[i]; for (int i = 0; i < n; i++) std::cin >> array[i];
std::cout << "Enter the value you want to search : "; std::cout << "Enter the value you want to search : ";
std::cin >> value; std::cin >> value;
re = search(array, value, n);
if (re == 0) re = interpolation_search(array, value, n);
if (re == -1)
std::cout << "Entered value is not in the array" << std::endl; std::cout << "Entered value is not in the array" << std::endl;
else else
std::cout << "The value is at the position " << re << std::endl; std::cout << "The value is at the position " << re << std::endl;
delete[] array;
return 0; return 0;
} }

26
search/interpolation_search2.cpp
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@ -1,4 +1,17 @@
/**
* \file
* \brief [Interpolation
* search](https://en.wikipedia.org/wiki/Interpolation_search) algorithm
*/
#include <iostream> #include <iostream>
/** function to search the value in an array using interpolation search
* \param [in] arr array to search in
* \param [in] value value to search for
* \param [in] len length of array
* \returns index where the value is found
* \returns -1 if not found
*/
int InterpolationSearch(int A[], int n, int x) { int InterpolationSearch(int A[], int n, int x) {
int low = 0; int low = 0;
int high = n - 1; int high = n - 1;
@ -11,18 +24,21 @@ int InterpolationSearch(int A[], int n, int x) {
else else
low = mid + 1; // x lies after mid low = mid + 1; // x lies after mid
} }
return -1; return -1;
} }
/** main function */
int main() { int main() {
int A[] = {2, 4, 5, 7, 13, 14, 15, 23}; int A[] = {2, 4, 5, 7, 13, 14, 15, 23};
int x = 17; int x = 17;
int index = InterpolationSearch(
A, 8, x); // passed array A inside the InterpolationSearch function ///< passed array A inside the InterpolationSearch function
if (index != -1) int index = InterpolationSearch(A, 8, x);
std::cout << "Number " << x << " is at " << index; if (index < 0)
std::cout << "Number " << x << " not found" << std::endl;
else else
std::cout << "Number " << x << " not found"; std::cout << "Number " << x << " is at " << index << std::endl;
} }
// randomly set x bcoz array was defined by us , therefore not reasonable for // randomly set x bcoz array was defined by us , therefore not reasonable for

18
search/jump_search.cpp
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@ -1,9 +1,14 @@
// C++ program to implement Jump Search /**
* \file
* \brief C++ program to implement [Jump
* Search](https://en.wikipedia.org/wiki/Jump_search)
*/
#include <algorithm> #include <algorithm>
#include <cmath> #include <cmath>
#include <iostream> #include <iostream>
/** jump search implementation
*/
int jumpSearch(int arr[], int x, int n) { int jumpSearch(int arr[], int x, int n) {
// Finding block size to be jumped // Finding block size to be jumped
int step = std::sqrt(n); int step = std::sqrt(n);
@ -14,7 +19,8 @@ int jumpSearch(int arr[], int x, int n) {
while (arr[std::min(step, n) - 1] < x) { while (arr[std::min(step, n) - 1] < x) {
prev = step; prev = step;
step += std::sqrt(n); step += std::sqrt(n);
if (prev >= n) return -1; if (prev >= n)
return -1;
} }
// Doing a linear search for x in block // Doing a linear search for x in block
@ -24,10 +30,12 @@ int jumpSearch(int arr[], int x, int n) {
// If we reached next block or end of // If we reached next block or end of
// array, element is not present. // array, element is not present.
if (prev == std::min(step, n)) return -1; if (prev == std::min(step, n))
return -1;
} }
// If element is found // If element is found
if (arr[prev] == x) return prev; if (arr[prev] == x)
return prev;
return -1; return -1;
} }

14
search/linear_search.cpp
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@ -1,5 +1,18 @@
/**
* \file
* \brief [Linear search
* algorithm](https://en.wikipedia.org/wiki/Linear_search)
*/
#include <iostream> #include <iostream>
/**
* Algorithm implementation
* \param [in] array array to search in
* \param [in] size length of array
* \param [in] key key value to search for
* \returns index where the key-value occurs in the array
* \returns -1 if key-value not found
*/
int LinearSearch(int *array, int size, int key) { int LinearSearch(int *array, int size, int key) {
for (int i = 0; i < size; ++i) { for (int i = 0; i < size; ++i) {
if (array[i] == key) { if (array[i] == key) {
@ -10,6 +23,7 @@ int LinearSearch(int *array, int size, int key) {
return -1; return -1;
} }
/** main function */
int main() { int main() {
int size; int size;
std::cout << "\nEnter the size of the Array : "; std::cout << "\nEnter the size of the Array : ";

75
search/median_search.cpp
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@ -1,42 +1,60 @@
/**
* \file
* \brief [Median search](https://en.wikipedia.org/wiki/Median_search) algorithm
* \warning This core is erroneous and gives invorrect answers. Tested using
* cases from [here](https://brilliant.org/wiki/median-finding-algorithm/)
* \ingroup median search
* \{
*/
#include <algorithm> #include <algorithm>
#include <cmath>
#include <deque>
#include <iostream> #include <iostream>
#include <iterator>
#include <stack>
#include <vector> #include <vector>
std::vector<int> v; /**
std::vector<int> s1; * @todo add documentation
std::vector<int> s2; */
std::vector<int> s3;
template <class X> template <class X>
void comp(X x) { void comp(X x, std::vector<int> *s1, std::vector<int> *s2,
if (s1.size() >= x && s1.size() + s2.size() < x) { std::vector<int> *s3) {
std::cout << s2[0] << " is the " << x + 1 << "th element from front"; if (s1->size() >= x && s1->size() + s2->size() < x) {
} else if (s1.size() > x) { std::cout << (*s2)[0] << " is the " << x + 1 << "th element from front";
std::sort(s1.begin(), s1.end()); } else if (s1->size() > x) {
std::cout << s1[x] << " is the " << x + 1 << "th element from front"; std::sort(s1->begin(), s1->end());
} else if (s1.size() + s2.size() <= x && s3.size() > x) { std::cout << (*s1)[x] << " is the " << x + 1 << "th element from front";
std::sort(s3.begin(), s3.end()); } else if (s1->size() + s2->size() <= x && s3->size() > x) {
std::cout << s3[x - s1.size() - s2.size()] << " is the " << x + 1 std::sort(s3->begin(), s3->end());
std::cout << (*s3)[x - s1->size() - s2->size()] << " is the " << x + 1
<< "th element from front"; << "th element from front";
} else { } else {
std::cout << x + 1 << " is invalid location"; std::cout << x + 1 << " is invalid location";
} }
} }
#define MAX_NUM 20 ///< maximum number of values to sort from
/**
* Main function
*/
int main() { int main() {
for (int i = 0; i < 1000; i++) { std::vector<int> v{25, 21, 98, 100, 76, 22, 43, 60, 89, 87};
v.push_back(std::rand() % 1000); std::vector<int> s1;
} std::vector<int> s2;
for (int r : v) { std::vector<int> s3;
std::cout << r << " ";
} // creates an array of random numbers
int median = std::rand() % 1000; // for (int i = 0; i < MAX_NUM; i++) {
// int r = std::rand() % 1000;
// v.push_back(r);
// std::cout << r << " ";
// }
for (int r : v) std::cout << r << " ";
int median = std::rand() % 1000; // initialize to a random numnber
std::cout << "\nmedian=" << median << std::endl; std::cout << "\nmedian=" << median << std::endl;
int avg1, avg2, avg3, sum1 = 0, sum2 = 0, sum3 = 0; int avg1, avg2, avg3, sum1 = 0, sum2 = 0, sum3 = 0;
for (int i = 0; i < 1000; i++) {
for (int i = 0; i < v.size(); i++) { // iterate through all numbers
if (v.back() == v[median]) { if (v.back() == v[median]) {
avg1 = sum1 + v.back(); avg1 = sum1 + v.back();
s2.push_back(v.back()); s2.push_back(v.back());
@ -49,9 +67,12 @@ int main() {
} }
v.pop_back(); v.pop_back();
} }
int x; int x;
std::cout << "enter the no. to be searched form begining:- "; std::cout << "enter the no. to be searched form begining:- ";
std::cin >> x; std::cin >> x;
comp(x - 1); comp(x - 1, &s1, &s2, &s3);
return 0; return 0;
} }
/// }

67
search/ternary_search.cpp
View File

@ -1,49 +1,57 @@
/* /**
* \file
* \brief [Ternary search](https://en.wikipedia.org/wiki/Ternary_search)
* algorithm
*
* This is a divide and conquer algorithm. * This is a divide and conquer algorithm.
* It does this by dividing the search space by 3 parts and * It does this by dividing the search space by 3 parts and
* using its property (usually monotonic property) to find * using its property (usually monotonic property) to find
* the desired index. * the desired index.
* *
* Time Complexity : O(log3 n) * * Time Complexity : O(log3 n)
* Space Complexity : O(1) (without the array) * * Space Complexity : O(1) (without the array)
*/ */
#include <iostream> #include <iostream>
/* /**
* The absolutePrecision can be modified to fit preference but * The absolutePrecision can be modified to fit preference but
* it is recommended to not go lower than 10 due to errors that * it is recommended to not go lower than 10 due to errors that
* may occur. * may occur.
* */
#define absolutePrecision 10
/**
* The value of _target should be decided or can be decided later * The value of _target should be decided or can be decided later
* by using the variable of the function. * by using the variable of the function.
*/ */
#define _target 10 #define _target 10
#define absolutePrecision 10
#define MAX 10000000
int N = 21; #define MAX 10000000 ///< Maximum length of array
int A[MAX] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 10};
/* /**
* get_input function is to receive input from standard IO * get_input function is to receive input from standard IO
* @todo @christianbender Get input from STDIO or write input to memory as done
* above.
*/ */
void get_input() { void get_input() {}
// TODO(christianbender): Get input from STDIO or write input to memory as
// done above.
}
/* /**
* This is the iterative method of the ternary search which returns the index of * This is the iterative method of the ternary search which returns the index of
* the element. * the element.
* \param[in] left lower interval limit
* \param[in] right upper interval limit
* \param[in] A array to search in
* \param[in] target value to search for
* \returns index where the target value was found
* \returns -1 if target value not found
*/ */
int it_ternary_search(int left, int right, int A[], int target) { int it_ternary_search(int left, int right, int A[], int target) {
while (1) { while (1) {
if (left < right) { if (left < right) {
if (right - left < absolutePrecision) { if (right - left < absolutePrecision) {
for (int i = left; i <= right; i++) for (int i = left; i <= right; i++)
if (A[i] == target) return i; if (A[i] == target)
return i;
return -1; return -1;
} }
@ -69,15 +77,22 @@ int it_ternary_search(int left, int right, int A[], int target) {
} }
} }
/* /**
* This is the recursive method of the ternary search which returns the index of * This is the recursive method of the ternary search which returns the index of
* the element. * the element.
* \param[in] left lower interval limit
* \param[in] right upper interval limit
* \param[in] A array to search in
* \param[in] target value to search for
* \returns index where the target value was found
* \returns -1 if target value not found
*/ */
int rec_ternary_search(int left, int right, int A[], int target) { int rec_ternary_search(int left, int right, int A[], int target) {
if (left < right) { if (left < right) {
if (right - left < absolutePrecision) { if (right - left < absolutePrecision) {
for (int i = left; i <= right; i++) for (int i = left; i <= right; i++)
if (A[i] == target) return i; if (A[i] == target)
return i;
return -1; return -1;
} }
@ -85,8 +100,10 @@ int rec_ternary_search(int left, int right, int A[], int target) {
int oneThird = (left + right) / 3 + 1; int oneThird = (left + right) / 3 + 1;
int twoThird = (left + right) * 2 / 3 + 1; int twoThird = (left + right) * 2 / 3 + 1;
if (A[oneThird] == target) return oneThird; if (A[oneThird] == target)
if (A[twoThird] == target) return twoThird; return oneThird;
if (A[twoThird] == target)
return twoThird;
if (target < A[oneThird]) if (target < A[oneThird])
return rec_ternary_search(left, oneThird - 1, A, target); return rec_ternary_search(left, oneThird - 1, A, target);
@ -99,10 +116,13 @@ int rec_ternary_search(int left, int right, int A[], int target) {
} }
} }
/* /**
* ternary_search is a template function * ternary_search is a template function
* You could either use it_ternary_search or rec_ternary_search according to * You could either use it_ternary_search or rec_ternary_search according to
* preference. * preference.
* \param [in] N length of array
* \param[in] A array to search in
* \param[in] target value to search for
*/ */
void ternary_search(int N, int A[], int target) { void ternary_search(int N, int A[], int target) {
std::cout << it_ternary_search(0, N - 1, A, target) << '\t'; std::cout << it_ternary_search(0, N - 1, A, target) << '\t';
@ -110,7 +130,10 @@ void ternary_search(int N, int A[], int target) {
std::cout << std::endl; std::cout << std::endl;
} }
/** Main function */
int main() { int main() {
int N = 21;
int A[] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 10};
get_input(); get_input();
ternary_search(N, A, _target); ternary_search(N, A, _target);
return 0; return 0;

16
search/searching.cpp → search/text_search.cpp
View File

@ -1,9 +1,17 @@
/**
* \file
* \brief Search for words in a long textual paragraph.
*/
#include <cstdlib> #include <cstdlib>
#include <iostream> #include <iostream>
#include <string> #ifdef _MSC_VER
#include <string> // required for MS Visual C++
char paragraph; #else
#include <cstring>
#endif
/** Main function
*/
int main() { int main() {
std::string paragraph; std::string paragraph;
std::cout << "Please enter your paragraph: \n"; std::cout << "Please enter your paragraph: \n";
@ -28,7 +36,7 @@ int main() {
<< paragraph.find(word) << std::endl << paragraph.find(word) << std::endl
<< std::endl; << std::endl;
} }
system("pause"); std::cin.get();
} }
} }
} }