3254. Find the Power of K-Size Subarrays I

You are given an array of integers nums of length n and a positive integer k.

The power of an array is defined as:

• Its maximum element if all of its elements are consecutive and sorted in ascending order.
• -1 otherwise.

You need to find the power of all subarrays of nums of size k.

Return an integer array results of size n - k + 1, where results[i] is the power of nums[i..(i + k - 1)].

class Solution {
public:
    vector<int> resultsArray(vector<int>& nums, int k) {
        deque<pair<int,int>> dq;
        vector<int> res;
        for(int i = 0; i < nums.size(); i++) {
            while(dq.size() and dq.back().second != nums[i] - 1) dq.pop_back();
            dq.push_back({i,nums[i]});
            while(dq.size() and dq.front().first <= i - k) dq.pop_front();
            if(i >= k - 1) {
                if(dq.size() == k) res.push_back(nums[i]);
                else res.push_back(-1);
            }
        }
        return res;
    }
};