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Update exponential_search.cpp

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Divide-et-impera-11 2019-11-29 03:02:08 +01:00 committed by GitHub
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Search/exponential_search.cpp
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@ -2,49 +2,43 @@
#include <string> #include <string>
#include <assert.h> #include <assert.h>
using namespaces std; using namespaces std;
//-----------------Binary Search Algorithm(use by Struzik algorithm)-----------------
//-----------------Binary Search Algorithm(use by struziki algorithm//-----------------
// 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 O(1)
// Space Complexity O(1) // Space Complexity O(1)
// Auxiliary Space Complexity O(1) // Auxiliary Space Complexity O(1)
template<class Type> inline Type* binary_search(Type *array, size_t size, Type key) {//Parameter List:Pointer to an array|size of array|key what you search
template<class Type> inline Type* binary_search(Type *array, size_t size, Type key) {//Parameter List:Pointer to and array|size of array|key what you search int32_t lower_index(0), upper_index(size - 1),middle_index; //lower_index => start of search range|upper_index => end of search range
int32_t lower_index(0), upper_index(size - 1),middle_index; //lower_index => start of search range | upper_index => end of search range | middle_index => middle of search range
while (lower_index <= upper_index) while (lower_index <= upper_index)
{ {
middle_index = floor((lower_index + upper_index) / 2); middle_index = floor((lower_index + upper_index) / 2);
if (*(array + middle_index) < key) lower_index = (middle_index + 1); //if the key is smaller than the middle of search range, we narrow the search range from up if (*(array + middle_index) < key) lower_index = (middle_index + 1); //narrow the search range from up
else if (*(array + middle_index) > key) upper_index = (middle_index - 1);//if the key is bigger than the middle of search range, we narrow the search range from down else if (*(array + middle_index) > key) upper_index = (middle_index - 1);//narrow the search range from down
else return (array + middle_index); //the key has been found else return (array + middle_index); //key has been found
} }
return nullptr; return nullptr;
} }
//-----------------Struzik Search Algorithm(Exponential)-----------------
//-----------------Struzik Search Algorithm(Exponential//-----------------
// Time Complexity O(log i)where i is the position of the search key in the list // Time Complexity O(log i)where i is the position of the search key in the list
// Worst Time Complexity O(log i) // Worst Time Complexity O(log i)
//Best Time Complexity Ω(1) // Best Time Complexity O(1)
// Space Complexity O(1) // Space Complexity O(1)
// Auxiliary Space Complexity O(1) // Auxiliary Space Complexity O(1)
template<class Type> Type* Struzik_Search(Type* array,size_t size,Type key) { // Parameter List:Pointer to an array|size of array|key what you search
template<class Type> Type* Struzik_Search(Type* array,size_t size,Type key) { //Parameter List: Pointer to an array(sorted)!You can use complex objectum, but in that case you have to overload '<>' operators!|size of array|key what you search uint32_t block_front(0),block_size = size == 0 ? 0 : 1; //block_front => start of search range|block_size => end of search range
uint32_t block_front(0),block_size = size == 0 ? 0 : 1; //the start and end of the first block where the algorithm starts seach !if the size of array 0 than return null pointer while (block_front != block_size) //if key bigger than last element itt will be equal and return nullptr
while (block_front != block_size) //when the start of block(block_front) and end of block(block_size) equal it means the key bigger than the last element of array and it return null pointer
{ {
if (*(array + block_size - 1) < key) {//if the key is bigger than the end of block we define a new block what is twice bigger than the previous if (*(array + block_size - 1) < key) {//if the key is bigger than the end of block we define a new block what is twice bigger than the previous
block_front = block_size; block_front = block_size;
(block_size * 2 - 1 < size) ? (block_size *= 2) : block_size = size;//if the end of new block bigger than size of array it takes the end of array (block_size * 2 - 1 < size) ? (block_size *= 2) : block_size = size;//if the end of new block bigger than size of array it takes the end of array
continue; continue;
} }
//when the algorithm delimit the block where the key shold be we do a binary search there return binary_search<Type>(array + block_front, (block_size - block_front), key);//if delimit the block where the key shold be,do binary search
return binary_search<Type>(array + block_front, (block_size - block_front), key);
} }
return nullptr; return nullptr;
} }
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 };
assert(Struzik_Search<int>(sorted_array, 7, 0) == nullptr);// Key smaller than the first element of array assert(Struzik_Search<int>(sorted_array, 7, 0) == nullptr);// Key smaller than the first element of array