题目描述:

链接: https://leetcode-cn.com/problems/binary-search/submissions/
题目:
用二分查找在一个有序数组当中找一个数, 有返回下标, 无返回-1.
示例 1:
输入: nums = [-1,0,3,5,9,12], target = 9
输出: 4
解释: 9 出现在 nums 中并且下标为 4

代码:

class Solution {
    public int search(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if (nums[mid] > target) {
                high = mid - 1;
            } else if (nums[mid] < target) {
                low = mid + 1;
            } else {
                return mid;
            }
        }
        return -1;
    }
}

水题, 不赘述.