OpenSoure_Repos/TheAlgorithms-C-Plus-Plus
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document binary search

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Krishna Vedala 2020-05-28 19:37:33 -04:00
parent 186c7a2de8
commit 94f3ffe146
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1 changed files with 38 additions and 18 deletions
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search/binary_search.cpp
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@ -1,35 +1,55 @@
/**
* @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])
return m; return m;
else if (key < a[m]) else if (key < a[m])
r = m - 1; r = m - 1;
else else
l = m + 1; l = m + 1;
} }
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
int res = binary_search(a, 0, n - 1, key); // this is use for find value in given array
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; delete[] a;
return 0; return 0;