The in-built STL library function binary_search() for searching whether a given string is present or not in the given string array. Binary search is a divide and conquers approach. The idea behind the binary search algorithm is to keep dividing the array in half until the element is found, or all the elements are exhausted. The middle item of the array is compared with the target value i.e. the value that needs to be searched, if it matches, it returns true otherwise if the middle term is greater than the target, the search is performed in the left sub-array. If the middle item is less than the target, the search is performed in the right sub-array.
Example:
Input: arr[] = {“Geeks”, “For”, “GeeksForGeek”}
Search “Geeks”
Output: String Founded in array
Syntax:
binary_search(starting_address, ending_address, value_of_string)
Below is the implementation of the above approach:
C++14
// C++ program to implement Binary// Search in Standard Template Library (STL)#include <algorithm>#include <iostream>using namespace std;void show_array(string arr[], int arraysize){ for (int i = 0; i < arraysize; i++) cout << arr[i] << ", ";}void binarySearch(string arr[], int size){ cout << "\nThe array is : \n"; show_array(arr, size); // Sort string array a for binary search as prerequisite sort(arr, arr + size); // Finding for "Geeks" cout << "\n\nSearching Result for \"Geeks\""; if (binary_search(arr, arr + size, "Geeks")) cout << "\nString Founded in array\n"; else cout << "\nString not Founded in array\n"; // Finding for string str string str = "Best"; cout << "\nSearching Result for \"Best\""; if (binary_search(arr, arr + size, str)) cout << "\nString Found in array"; else cout << "\nString not Found in array";}// Driver codeint main(){ // Initialising string array a string arr[] = { "Geeks", "For", "GeeksForGeek" }; // Find size of array arr int size = sizeof(arr) / sizeof(arr[0]); // Function call binarySearch(arr, size); return 0;} |
The array is : Geeks, For, GeeksForGeek, Searching Result for "Geeks" String Founded in array Searching Result for "Best" String not Found in array
Time Complexity: O(N*log N), where N represents the number of elements present in the array
Auxiliary Space: O(1)
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