Today I have done leetcode's August LeetCoding Challenge with cpp.

August LeetCoding Challenge 16

Description

Sliding Window Maximum

You are given an array of integers nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves right by one position.

Return the max sliding window.

Example 1:

Input: nums = [1,3,-1,-3,5,3,6,7], k = 3
Output: [3,3,5,5,6,7]
Explanation: 
Window position                Max
---------------               -----
[1  3  -1] -3  5  3  6  7       3
 1 [3  -1  -3] 5  3  6  7       3
 1  3 [-1  -3  5] 3  6  7       5
 1  3  -1 [-3  5  3] 6  7       5
 1  3  -1  -3 [5  3  6] 7       6
 1  3  -1  -3  5 [3  6  7]      7

Example 2:

Input: nums = [1], k = 1
Output: [1]

Constraints:

• 1 <= nums.length <= 105
• -104 <= nums[i] <= 104
• 1 <= k <= nums.length

Solution

class Solution {
public:
  vector<int> maxSlidingWindow(vector<int>& nums, int k) {
    deque<int> monoQueue;
    for(int i = 0; i < k; ++i) {
      while(monoQueue.size() && monoQueue.back() < nums[i]) monoQueue.pop_back();
      monoQueue.push_back(nums[i]);
    }
    vector<int> answer{monoQueue.front()};
    for(int i = k; i < nums.size(); ++i) {
      while(monoQueue.size() && monoQueue.back() < nums[i]) monoQueue.pop_back();
      if(monoQueue.size() && monoQueue.front() == nums[i-k]) monoQueue.pop_front();
      monoQueue.push_back(nums[i]);
      answer.push_back(monoQueue.front());
    }
    return answer;
  }
};

// Accepted
// 51/51 cases passed (199 ms)
// Your runtime beats 91.73 % of cpp submissions
// Your memory usage beats 45.65 % of cpp submissions (134.7 MB)