binarySearch

#include <iostream>
int binarySearch(int *a, int size, int key) {
    int left, right, mid;
    left = 0;
    right = size - 1;

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

    return -1;                  // не найден
}

int main() {
    int size = 12;
    int *a = new int[size];

    for(int i = 0; i < size; i++)
        a[i] = i*i;

    for(int i = 0; i < size; i++)
        std::cout << a[i] << " ";
    std::cout << std::endl;

    std::cout << binarySearch(a, size, 121) << std::endl;


    return 0;
}