二分查找

 1 /**
 2  * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 3  *
 4  * 
 5  * @param nums int整型一维数组 
 6  * @param target int整型 
 7  * @return int整型
 8  */
 9 function search( nums ,  target ) {
10     // write code here
11     let left = 0;
12     let right = nums.length - 1;
13     while(left <= right){
14        let mid = Math.floor(left + (right - left)/2);
15         if(nums[mid] === target){
16             return mid;
17         }else if(target < nums[mid]){
18             right = mid -1 ;
19         }else if(target > nums[mid]){
20             left = mid + 1;
21         }
22     }
23      return -1;
24 }
25 module.exports = {
26     search : search
27 };