LeetCode.1438 Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit

1.Problem
https://leetcode.com/problems/longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit/

2.Idea
MaxMinQueue + 2 Pointers method

3.Source

 class MaxMinQueue {  
 public:  
      MaxMinQueue() {}  
      bool empty() { return elements.empty(); }  
      int size() { return elements.size(); }  
      void push(int val) {  
           elements.push(val);  
           while (!maxElements.empty() && val > maxElements.back()) maxElements.pop_back();  
           maxElements.push_back(val);  
           while (!minElements.empty() && val < minElements.back()) minElements.pop_back();  
           minElements.push_back(val);  
      }  
      int pop() {  
           int val = elements.front();  
           elements.pop();  
           if (val == maxElements.front()) maxElements.pop_front();  
           if (val == minElements.front()) minElements.pop_front();  
           return val;  
      }  
      int peekMax() {  
           return maxElements.front();  
      }  
      int peekMin() {  
           return minElements.front();  
      }  
 private:  
      queue<int> elements;  
      deque<int> maxElements;  
      deque<int> minElements;  
 };  
 class Solution {  
 public:  
      MaxMinQueue q;  
      int longestSubarray(vector<int>& nums, int limit) {  
           int n = nums.size();  
           int ans = 0;  
           int p1 = 0;  
           while (p1 < n) {  
                q.push(nums[p1]);  
                while(q.size() > 0 && (q.peekMax() - q.peekMin() > limit)) {  
                     q.pop();  
                }  
                ans = max(ans, q.size());  
                p1++;  
           }  
           return ans;  
      }  
 };  
 int main()  
 {  
      Solution obj;  
      vector<int> in = { 8,2,4,7 };  
      obj.longestSubarray(in, 4);  
      return 0;  
 }