two stacks in array

Author: RisingGeek

GeeksforGeeks/Stack/two_stacks_in_array.cpp

@@ -0,0 +1,112 @@
+
+/*
+Problem link- https://practice.geeksforgeeks.org/problems/implement-two-stacks-in-an-array/1
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+class twoStacks
+{
+    int *arr;
+    int size;
+    int top1, top2;
+public:
+   twoStacks(int n=100){size = n; arr = new int[n]; top1 = -1; top2 = size;}
+
+   void push1(int x);
+   void push2(int x);
+   int pop1();
+   int pop2();
+};
+int main()
+{
+    int T;
+    cin>>T;
+    while(T--)
+    {
+        twoStacks *sq = new twoStacks();
+        int Q;
+        cin>>Q;
+        while(Q--){
+        int stack_no;
+        cin>>stack_no;
+        int QueryType=0;
+        cin>>QueryType;
+
+        if(QueryType==1)
+        {
+            int a;
+            cin>>a;
+            if(stack_no ==1)
+            sq->push1(a);
+            else if(stack_no==2)
+            sq->push2(a);
+        }else if(QueryType==2){
+        	if(stack_no==1)
+            cout<<sq->pop1()<<" ";
+            else if(stack_no==2)
+            cout<<sq->pop2()<<" ";
+        }
+        }
+        cout<<endl;
+    }
+}
+
+/*This is a function problem.You only need to complete the function given below*/
+/*The structure of the class is
+class twoStacks
+{
+    int *arr;
+    int size;
+    int top1, top2;
+public:
+   twoStacks(int n=100){size = n; arr = new int[n]; top1 = -1; top2 = size;}
+
+   void push1(int x);
+   void push2(int x);
+   int pop1();
+   int pop2();
+};
+*/
+/* The method push to push element into the stack 2 */
+void twoStacks :: push1(int x)
+{
+    if(top1<top2-1) {
+        arr[++top1]=x;
+    }
+    else cout<<"stack overflow";
+}
+
+/* The method push to push element into the stack 2*/
+void twoStacks ::push2(int x)
+{
+    if(top1<top2-1) {
+        arr[--top2]=x;
+    }
+    else cout<<"stack overflow";
+}
+
+/* The method pop to pop element from the stack 1 */
+//Return the popped element
+int twoStacks ::pop1()
+{
+    if(top1>=0) {
+        top1--;
+        return arr[top1+1];
+    }
+    else {
+        return -1;
+    }
+}
+/* The method pop to pop element from the stack 2 */
+//Return the popped element
+int twoStacks :: pop2()
+{
+    if(top2<size) {
+        top2++;
+        return arr[top2-1];
+    }
+    else {
+        return -1;
+    }
+}