75 lines
1.7 KiB
Java
75 lines
1.7 KiB
Java
/* Program to reverse a Stack using Recursion*/
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import java.util.Stack;
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public class ReverseStackUsingRecursion {
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//Stack
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private static Stack<Integer> stack=new Stack<>();
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//Main function
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public static void main(String[] args) {
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//To Create a Dummy Stack containing integers from 0-9
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for(int i=0;i<10;i++)
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{
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stack.push(i);
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}
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System.out.println("STACK");
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//To print that dummy Stack
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for(int k=9;k>=0;k--)
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{
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System.out.println(k);
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}
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//Reverse Function called
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reverseUsingRecursion(stack);
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System.out.println("REVERSED STACK : ");
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//To print reversed stack
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while (!stack.isEmpty())
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{
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System.out.println(stack.pop());
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}
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}
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//Function Used to reverse Stack Using Recursion
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private static void reverseUsingRecursion(Stack<Integer> stack) {
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if(stack.isEmpty()) // If stack is empty then return
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{
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return;
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}
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/* All items are stored in call stack until we reach the end*/
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int temptop=stack.peek();
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stack.pop();
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reverseUsingRecursion(stack); //Recursion call
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insertAtEnd(temptop); // Insert items held in call stack one by one into stack
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}
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//Function used to insert element at the end of stack
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private static void insertAtEnd(int temptop) {
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if(stack.isEmpty())
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{
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stack.push(temptop); // If stack is empty push the element
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}
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else {
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int temp = stack.peek(); /* All the items are stored in call stack until we reach end*/
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stack.pop();
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insertAtEnd(temptop); //Recursive call
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stack.push(temp);
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}
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}
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}
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