Create maxQueue-using-deque.cpp

max-queue using deque (which can be done  with 2 stack also)

Author: sagsango

Min-Max Stack-Queue/maxQueue-using-deque.cpp

@@ -0,0 +1,38 @@
+// submission link: https://leetcode.com/problems/sliding-window-maximum/
+
+
+struct maxQueue {
+    deque<pair<int, int>> q; // we maintain decreasing order
+    int _size;
+    maxQueue() {
+        _size = 0;
+    }
+    void push(int num) {
+        int inFront = 0;
+        while (!q.empty() && q.back().first < num) {
+            inFront += q.back().second + 1; // previous_deletions + curent_deletions
+            q.pop_back();
+        }
+        q.push_back({num, inFront});
+        _size += 1;
+    }
+
+    int max() {
+        return q.front().first;
+    }
+
+    void pop() {
+        int num = q.front().first;
+        int inFront = q.front().second;
+        q.pop_front();
+        if (inFront) {
+            inFront -= 1;
+            q.push_front({num, inFront});
+        }
+        _size -= 1;
+    }
+
+    int size() {
+        return _size;
+    }
+};