二分搜索

#include <iostream>
#include <vector>
#include <string>

using namespace std;

//二分搜索

int binarySearch(int a[],int length,int data) {
    int left = 0;
    int right = length - 1;

    int index = -1;
    while (left <= right)
    {
        int mid = (left + right) / 2;
        if(a[mid] > data) {
            right = mid - 1;
        } else if(a[mid] < data) {
            left = mid + 1;
        } else {
            index = mid;
            break;
        }
    }
    
    return index;
}

int main() {
    int a[] = {1,2,3,4,5};
    int index = binarySearch(a,5,3);

    cout<<index<<endl;
}