LeetCode 704 二分查找

class Solution {
    public:
        int search(vector<int>& nums, int target) {
            int n=nums.size();
            
            int left=0;
            int right=n-1;
            bool flag=0;
            int result=0;
            while(left<=right){//注意小于等于
                int mid=(left+right)/2;
                if(nums[mid]==target){
                    flag=1;//存在目标值
                    result=mid;
                    break;
                }
                else if(nums[mid]>target){
                   right=mid-1;
                }
                else{
                    left=mid+1;
                
                }
            }
            if(flag){
                return result;
            }else{
                return -1;
            }
        }
    };