• 這是一題簡單的定長度 sliding window。先排序再用滑動窗口求值。時間複雜度是 O(nlog⁡(n))O(n\log(n))
class Solution {
public:
    int minimumDifference(vector<int>& nums, int k) {
        sort(nums.begin(), nums.end());
        int res = INT_MAX;
        for (int i = 0; i < nums.size() - k + 1; i++) {
            res = min(res, nums[i+k-1] - nums[i]);
        }
        return res;
    }
};