二分查找入门

public static int search(int[] nums, int target) {
        //双指针
        int left=0,right=nums.length-1;
        int mid=0;
        int res = -1;
        while (left<=right){
            //防止int溢出如果是写为（left+right）/2 可能会很大
            mid=left+(right-left)/2;
            if (nums[mid]==target){
                res=mid;
                break;
            }if (nums[mid]>target){
                right = mid - 1;
            }else {
                left = mid + 1;
            }
        }
        return res;
    }