二分查找

#include <iostream>
#include <vector>
using namespace std;

int data[10] = {1,2,3,4,5,6,7,8,9,10};
void search(int x)
{
    int left = 0;
    int right = sizeof(data)/4-1;
    int middle = 0;
    while(right != left)
    {
        middle = left + (right - left) / 2;
        if(data[middle] > x)
        {
            right = middle -1;
        }
        else if(data[middle] < x)
        {
            left = middle + 1;
        }
        else{
            cout<<"find data is at "<<middle<<endl;
            break;
        }
    }
    if(right == left)
    {
        if(x == data[right])
        {
            cout<<"find data is at "<<right<<endl;
        }
        else{
            cout<<"not find data"<<endl;
        }
    }
}

int main()
{
    search(10);
}

时间复杂度nlg(n)