int binarySearch(int a[], int startIndex, int endIndex, const int target)
{
    int left = startIndex;
    int right = endIndex;
    while(left <= right)
    {
        int middle = ((right - left) >> 1) + left;  //位运算提高效率，用减法防溢出。
        if(a[middle] < target)      //对于指令流水，考虑分支预测，
            left = middle + 1;
        else if(a[middle] > target)
            right = middle - 1;
        else
            return middle;
        /*
        bool flag = (target != a[middle]);
        if(flag)    //分支可预测性增强，查找的最后一次才会预测失败
            (a[middle] < target) ? (left = middle + 1) : (right = middle - 1);
        else
            return middle;
        */
    }
    return -1;
}