Merge pull request #300 from GuptaTanisha/master

New Algorithm Create stack_using_two_queues.cpp

Author: abranhe

algorithms/data-structures/stack/stack_using_two_queues.cpp

@@ -0,0 +1,66 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+class QueueStack{
+private:
+    queue<int> q1;
+    queue<int> q2;
+public:
+    void push(int);
+    int pop();
+};
+
+
+int main()
+{
+    int T;
+    cin>>T;
+    while(T--)
+    {
+        QueueStack *qs = new QueueStack();
+
+        int Q;
+        cin>>Q;
+        while(Q--){
+        int QueryType=0;
+        cin>>QueryType;
+        if(QueryType==1)
+        {
+            int a;
+            cin>>a;
+            qs->push(a);
+        }else if(QueryType==2){
+            cout<<qs->pop()<<" ";
+
+        }
+        }
+        cout<<endl;
+    }
+}
+
+class QueueStack{
+private:
+    queue<int> q1;
+    queue<int> q2;
+public:
+    void push(int);
+    int pop();
+};
+void QueueStack :: push(int x)
+{
+        q2.push(x);
+        while(!q1.empty()){
+            q2.push(q1.front());
+            q1.pop();
+        }
+        swap(q1,q2);
+}
+int QueueStack :: pop()
+{
+         if(q1.empty()) return -1;
+        else{
+            int x = q1.front();
+            q1.pop();
+            return x;
+        }
+}