只利用一个额外栈实现栈的排序

package chapter01_stack_and_queue;

import java.util.Stack;

public class _05_StackSortStack {
public static void sortStackByStack(Stack<Integer> stack) {
Stack<Integer> stackHelp = new Stack<Integer>();
while(!stack.isEmpty()) {
int cur = stack.pop();
while(!stackHelp.isEmpty() && stackHelp.peek() < cur) {
stack.push(stackHelp.pop());
}
stackHelp.push(cur);
}
while (!stackHelp.isEmpty()) {
stack.push(stackHelp.pop());
}
}

public static void main(String[] args) {
Stack<Integer> stack = new Stack<Integer>();
stack.push(3);
stack.push(1);
stack.push(6);
stack.push(2);
stack.push(5);
stack.push(4);
sortStackByStack(stack);
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.pop());
}
}