BinarySearch(C++)

binary_search.cpp

#include <iostream>
#include <algorithm>
 
//二分探索
bool mybinary_search( const int a[], const unsigned int start_idx, const unsigned int end_idx, const int target, int& idx){
	unsigned int start = start_idx;
	unsigned int end = end_idx;
	while((end - start) >= 0){
		int mid = (end + start) / 2;
		if(a[mid] == target){
			idx = mid;
			return true;
		}else if(a[mid] > target){
			end = mid - 1;
		}else {
			start = mid + 1; 
		}
	}
	return false;
}

int main() {
	int N = 10;
	int A[N] = {20, 10, 30, 40, 50, 60, 80, 90, 70, 100};
	std::sort(A, A+N);
	int target = 100;
	int idx = -1;
	if(mybinary_search(A, 0, N - 1, target, idx)){
		std::cout << "Success:" << idx << std::endl;
	}
	
	//std::binary_search Test
	if (std::binary_search(A, A+N, 75)) {
		std::cout << "Success" << std::endl;	
	}
	return 0;
}