CTCI 3.6

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Write a program to sort a stack in ascending order (with biggest items on top). You may use at most one additional stack to hold items, but you may not copy the elements into any other data structure (such as an array).The stack supports the following operations: push, pop, peek, and isEmpty.

/*Use bubble sort, one stack used as buffer as well as to store the sorted elements. Each time find the smallest element exist in the other stack and push it in after pop the buffer out.*/import java.util.*;public class SortStack {    Stack<Integer> stack2 = new Stack<Integer>();    public void sort(Stack<Integer> stack1) {        int min = 0, temp = 0, cnt = 0;        while(stack1.isEmpty() == false) {            stack2.push(stack1.pop());            cnt++;        }        for(int i = 0; i < cnt; i++) {            min = stack2.pop();            while(stack2.isEmpty() == false) {                temp = stack2.pop();                if(temp >= min) {                    stack1.push(temp);                }                else {                    stack1.push(min);                    min = temp;                }            }            for(int j = 0; j < cnt-i-1; j++) {                stack2.push(stack1.pop());            }            stack1.push(min);        }    }    public void print(Stack<Integer> stack) {        while(stack.isEmpty() == false) {            System.out.print(stack.pop() + " ");        }        System.out.print("");    }    public static void main(String[] args) {        Stack<Integer> stack1 = new Stack<Integer>();        stack1.push(10); stack1.push(8); stack1.push(18); stack1.push(8); stack1.push(1);        SortStack ss = new SortStack();        ss.sort(stack1);        ss.print(stack1);    }}