leetcode 二分查找应用

34. Find First and Last Position of Element in Sorted Array

代码：

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        int low = lowwer_bound(nums,target);
        int high = upper_bound(nums,target);

        if(low == high)
            return {-1,-1};

        return {low,high-1};
    }
    int lowwer_bound(vector<int>& nums,int target)
    {
        int left = 0;
        int right = nums.size();
        int mid = 0;
        while(left < right){
            mid = left + ((right-left)>>1);
            if(nums[mid]>=target){
                right = mid;
            }else{
                left = mid + 1;
            }
        }
        return left;
    }
    int upper_bound(vector<int>& nums,int target){
        int left = 0;
        int right = nums.size();
        int mid = 0;
        while(left < right){
            mid = left + ((right - left)>>1);
            if(nums[mid]>target){
                right = mid;
            }else{
                left = mid +1;
            }
        }
        return left;
    }
};