leetcode---Search for a Range

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm’s runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,

Given [5, 7, 7, 8, 8, 10] and target value 8,

return [3, 4].

class Solution {
public:
vector<int> searchRange(vector<int>& nums, int target)
{
vector<int> ans;
int l = lower_bound(nums.begin(), nums.end(), target) - nums.begin();
int r = upper_bound(nums.begin(), nums.end(), target) - nums.begin();
if(l < r)
{
ans.push_back(l);
ans.push_back(r-1);
}
else
{
ans.push_back(-1);
ans.push_back(-1);
}
return ans;
}
};