Complete program of Reversal of a stack using recursion in java
import java.util.Scanner;
import java.util.Stack;
public class ReverseStack {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number of elements you wish to insert in the stack");
int n = sc.nextInt();
int i;
Stack<Integer> stack = new Stack<Integer>();
System.out.println("Enter the stack elements");
for (i = 0; i < n; i++) {
stack.push(sc.nextInt());
}
sc.close();
reverseStack(stack);
System.out.println("The reversed stack is:");
while (!stack.isEmpty()) {
System.out.print(stack.peek() + ",");
stack.pop();
}
}
private static void reverseStack(Stack<Integer> stack) {
if (stack.isEmpty()) {
return;
}
//Store the topmost element
int element = stack.peek();
//Remove the topmost element
stack.pop();
//Reverse the stack for the leftover elements
reverseStack(stack);
//Insert the topmost element to the bottom of the stack
insertAtBottom(stack, element);
}
private static void insertAtBottom(Stack<Integer> stack, int element) {
if (stack.isEmpty()) {
//When stack is empty, insert the element so it will be present at the bottom of the stack
stack.push(element);
return;
}
int ele = stack.peek();
/*Keep popping elements till stack becomes empty. Push the elements once the topmost element has
moved to the bottom of the stack.
*/
stack.pop();
insertAtBottom(stack, element);
stack.push(ele);
}
}