[CC150v4] 3.6 Sort Stack

Question

Write a program to sort a stack in ascending order. You should not make any assumptions about how the stack is implemented.

The following are the only functions that should be used to write this program: push | pop | peek | isEmpty.

Solution

This is a very good question that tests stack operations.

Code

written by me

public static Stack<Integer> sort(Stack<Integer> s) {
    Stack<Integer> result = new Stack<Integer>();
    while (!s.isEmpty()) {
        Integer nextNum = s.pop();
        while (!result.isEmpty() && result.peek() < nextNum) {
            s.push(result.pop());
        }
        result.push(nextNum);
    }
    return result;
}