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 stack) {
		Stack stackHelp = new Stack();
		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 stack = new Stack();
		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());
	}
}