在升序数组中找到 target 的范围

要求

自然想到二分查找

1. 查找下限
   nums[mid]<target left=mid;
   else right=mid;
2. 查找上限
   nums[mid]>target right = mid
   else left = mid

class Solution
{
public:
    vector<int> searchRange(vector<int>& nums, int target)
    {
        vector<int> res(2, -1);
        int size = nums.size();
        if (size == 0) return res;
        int left = 0, right = size - 1;
        while (right > left)
        {
            int mid = (left + right) / 2;
            if (nums[mid] < target)
                left = mid + 1;
            else
                right = mid;
        }
        if (nums[left] == target)
            res[0] = left;
        else
            return res;
        left = 0;
        right = size - 1;
        while (left < right)
        {
            int mid = (left + right + 1) / 2;
            if (nums[mid] > target)
                right = mid - 1;
            else
                left = mid;
        }
        res[1] = right;
        return res;
    }
};

✔ Accepted
✔ 88/88 cases passed (8 ms)
✔ Your runtime beats 92.89 % of cpp submissions
✔ Your memory usage beats 76.77 % of cpp submissions (10.3 MB)