解题思路：

二分查找主要分为[ left , right ]左闭右闭和[ left , right )左闭右开两种

此处采取[ left , right ]左闭右闭写法 

注意：

1. right的初始化取值

2. while中取等

3. right = mid -1 ;

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