Description

Submission I

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        int beg = 0, end = k - 1;
        multiset<int> Set;

        for(int i = beg; i <= end; ++i) {
            Set.insert(nums[i]);
        }

        vector<int> rets;
        rets.push_back(*Set.rbegin());
        cout << *Set.rbegin();
        while(end < nums.size()) {
            Set.erase(Set.lower_bound(nums[beg++]));
            end++;
            if(end >= nums.size()) break;
            Set.insert(nums[end]);
            rets.push_back(*Set.rbegin());
        }

        return rets;

    }
};

Submission II

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        int n = nums.size();
        vector<int> skipped(n, 0);
        deque<int> dq;

        vector<int> rets;
        for(int i = 0; i < n; ++i) {
            if(dq.empty() || nums[i] <= nums[dq.back()]) {
                dq.push_back(i);
            } else {
                while(!dq.empty() && nums[dq.back()] <= nums[i]) {
                    dq.pop_back();
                }
                dq.push_back(i);
            }
            if(i + 1 >= k) {
                rets.push_back(nums[dq.front()]);
            }

            if(i - dq.front() >= k-1) {
                dq.pop_front();
            }
        }

        return rets;
    }
};

// 3 -1

References

1. https://www.youtube.com/watch?v=b1rqOQ5p6EA

Submission III 210703

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        deque<int> dq;  // index

        vector<int> rets;
        for(int i = 0; i < nums.size(); ++i) {
            while(!dq.empty() && i - dq.front() >= k) dq.pop_front();
            while(!dq.empty() && nums[dq.back()] < nums[i]) dq.pop_back();
            dq.push_back(i);
            if(i >= k - 1)
                rets.push_back(nums[dq.front()]);
        }

        return rets;
    }
};

// [1  3  -1] -> [3, -1]