leetcode-----34. 在排序数组中查找元素的第一个和最后一个位置

• 链接：https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/

代码

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 - l) / 2;
            if (nums[mid] >= target) r = mid;
            else l = mid + 1;
        }
        if (nums[r] != target) return {-1, -1};
        int L = r;

        l = 0 , r = nums.size() - 1;
        while (l < r) {
            int mid = (l + r + 1) / 2;
            if (nums[mid] <= target) l = mid;
            else r = mid - 1;
        }
        return {L, r};
    }
};