34_在排序数组中查找元素的第一个和最后一个位置.cpp

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        if(nums.empty()) return {-1, -1};
        int l = 0, r = nums.size() - 1;
        while(l < r) {
            int mid = l + r >> 1;
            if(nums[mid] >= target) r = mid;
            else l = mid + 1;
        }
        if(nums[l] != target) return {-1, -1};
        int L = l;

        l = 0, r = nums.size() - 1;
        while(l < r) {
            int mid = (l + r) + 1 >> 1;
            if(nums[mid] <= target) l = mid;
            else r = mid - 1;
        }
        return {L, r};
    }
};