提示:当left和right都是非负数时,使用 mid = left + (right - left) / 2;这种形式可以避免溢出。
当left和right一个为负另一个为非负时,用mid = (left + right) / 2;这种形式可以避免溢出。
- int search_first_larger_k(int* arr, int length, int k)
- {
- if (arr == nullptr || length <= 0 || arr[length - 1] <= k)
- return -1;
- int res = length - 1,left=0,right=length-1;
- while (left <= right)//不需要加判断条件 && right>=0 && left<length
- {
- //int mid = (left + right) / 2; 这种方法会溢出!!!!
- int mid = left + (right - left) / 2;
- if (arr[mid] > k)
- {
- res = mid;
- right = mid - 1;
- }
- else// if (arr[mid] <= k)
- left = mid + 1;
- }
- return res;
- }