Using one stack to sort another stack

subject ： The type of elements in a stack is integer , Now I want to sort the stack from top to bottom in the order of big to small , Only one stack is allowed . besides , You can apply for new variables , But you can't apply for additional data structures . How to sort ？

answer ： Mark the stack to be sorted as stack, The other stack is help, take stack The top element of the stack pops up , and help Stack top element comparison ,stack The top element of the stack is less than or equal to help The top element of the stack is stack Put the top element of the stack into heip Go in the stack , Otherwise, I will help The elements of spring out one by one , Put them one by one stack In the stack . Repeat the above steps , until stack Stack empty until . After the above operation , here help The order of elements in the stack is from top to bottom, from small to large . Finally, just put help Put the elements in the stack one by one stack Just in the stack .

Code ：

public void sort(){
    public Stack<int> help=new Stack<int>();
    while(!stack.empty()){
        int cur=stack.pop();
        while(!help.empty()&&cur>help.peek(){
            stack.push(help.pop());}
        
        help.push(cur);}
    while(!help.empty()){
        stack.push(help.pop());}}