学步园

写二分的时候经常要测试好久边界问题。有人给出了一个一般使用的方法

http://blog.csdn.net/v_july_v/article/details/7093204

//right=n-1 => while(left <= right) => right=middle-1;

//right=n => while(left < right) => right=middle;

 
int binary_search(int array[],int n,int value)  
{  
    int left=0;  
    int right=n-1;
  
    while (left<=right)          //循环条件，适时而变  
    {  
        int middle=left + ((right-left)>>1);  //防止溢出  
  
        if (array[middle]>value)  
        {  
            right =middle-1;   //right赋值，适时而变  
        }   
        else if(array[middle]<value)  
        {  
            left=middle+1;  
        }  
        else  
            return middle;
    }  
    return -1;  
}