二分查找

#include <iostream>
using namespace std;

int binarySearch(int arr[],int low,int high,int key){
    if(low > high){
        return -1;
    }
    int mid = low + ((high - low)>>1);
    int midVal = arr[mid];
    if(midVal > key){
        binarySearch(arr,low,mid-1,key);
    }else if(midVal < key){
        binarySearch(arr,mid+1,high,key);
    }else{
        return mid;
    }
}

int main() {
    int a[] = {1,11,23,34,45,56,78,90,99};
    int res = binarySearch(a, 0, (sizeof(a) / sizeof(a[0]))-1, 23);
    cout<<"res = "<<res<<endl;
    return 0;
}