Sudo Placement[1.3] | Stack Design
Given q number of queries, you need to perform operations on the stack. Queries are of three types 1, 2, and 3. If the operation is to push (1) then push the elements, if the operations are to pop (2) then pop the element and if it is Top (3), then print the element at the top of the stack (If the stack is empty, print “-1”, without quotes).
Examples:
Input: Queries = 6 3 1 5 1 6 1 7 2 3 Output: -1 6 The first query is to print top, but since the stack is empty, so we print -1. Next three queries are to push 5, 6, and 7, so we pushed them on a stack. Next query is pop, so we popped 7 from a stack. Final query is to print the top, so 6 is there at the top and thus printed.
Approach:
Stack can be used to perform the given operation. If the input for a query is 1, then take another input and push the element into the stack using the push() function. If the input for a query is 2, then pop the element using the pop() function in a stack. If the input for a query is 3, then print the top element using the top() function.
Below is the implementation of the above approach:
C++
// C++ program for // Sudo-Placement | Stack Design #include <bits/stdc++.h> using namespace std; stack< int > s; // function to perform type-1 operation void _push( int n) { s.push(n); } // function to perform type-2 operation void _pop() { s.pop(); } // function to perform type-3 operation void print() { // if the stack is not empty if (!s.empty()) cout << s.top() << endl; else cout << -1 << endl; } // Driver Code int main() { // 1st query print(); // 2nd query _push(5); // 3rd query _push(6); // 4th query _push(7); // 5th query _pop(); // 6th query print(); return 0; } |
Java
import java.util.*; // Java program for // Sudo-Placement | Stack Design class GFG { static Stack<Integer> s = new Stack<>(); // function to perform type-1 operation static void _push( int n) { s.push(n); } // function to perform type-2 operation static void _pop() { s.pop(); } // function to perform type-3 operation static void print() { // if the stack is not empty if (!s.empty()) { System.out.println(s.peek()); } else { System.out.println(- 1 ); } } // Driver Code public static void main(String[] args) { // 1st query print(); // 2nd query _push( 5 ); // 3rd query _push( 6 ); // 4th query _push( 7 ); // 5th query _pop(); // 6th query print(); } } // This code contributed by Rajput-Ji |
Python3
# Python3 program for # Sudo-Placement | Stack Design s = []; # function to perform # type-1 operation def _push(n): s.append(n); # function to perform # type-2 operation def _pop(): s.pop(); # function to perform # type-3 operation def _print(): # if the stack is not # empty if ( len (s) > 0 ): print (s[ len (s) - 1 ]); else : print ( "-1" ); # Driver Code if __name__ = = '__main__' : # 1st query _print(); # 2nd query _push( 5 ); # 3rd query _push( 6 ); # 4th query _push( 7 ); # 5th query _pop(); # 6th query _print(); # This code is contributed by 29AjayKumar |
C#
// C# program for // Sudo-Placement | Stack Design using System; using System.Collections.Generic; class GFG { static Stack< int > s = new Stack< int >(); // function to perform type-1 operation static void _push( int n) { s.Push(n); } // function to perform type-2 operation static void _pop() { s.Pop(); } // function to perform type-3 operation static void print() { // if the stack is not empty if (s.Count != 0) { Console.WriteLine(s.Peek()); } else { Console.WriteLine(-1); } } // Driver Code public static void Main() { // 1st query print(); // 2nd query _push(5); // 3rd query _push(6); // 4th query _push(7); // 5th query _pop(); // 6th query print(); } } /* This code contributed by PrinciRaj1992 */ |
Javascript
<script> // Javascript program for // Sudo-Placement | Stack Design let s=[]; // function to perform type-1 operation function _push(n) { s.push(n); } // function to perform type-2 operation function _pop() { s.pop(); } // function to perform type-3 operation function print() { // if the stack is not empty if (s.length!=0) { document.write(s[s.length-1]+ "<br>" ); } else { document.write(-1+ "<br>" ); } } // Driver Code // 1st query print(); // 2nd query _push(5); // 3rd query _push(6); // 4th query _push(7); // 5th query _pop(); // 6th query print(); // This code is contributed by rag2127 </script> |
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