Topic: give you a stack, you reverse the stack, can not apply for additional data structure, only use a recursive function. How to achieve?
See "Programmer Code Interview Guide" P7 details.
package com.gxu.dawnlab_algorithm8;
import java.util.Stack;
/**
* 给你一个栈,请你逆序这个栈,不能申请额外的数据结构,只能
* 使用递归函数。如何实现?
* @author junbin
*
* 2019年7月12日
*/
public class ReverseStackUsingRecursive {
public static void reverse(Stack<Integer> stack) {
if (stack.isEmpty()) {
return;
}
int i = getAndRemoveLastElement(stack);
reverse(stack);
stack.push(i);
}
public static int getAndRemoveLastElement(Stack<Integer> stack) {
int result = stack.pop();
if (stack.isEmpty()) {
return result;
} else {
int last = getAndRemoveLastElement(stack);
stack.push(result);
return last;
}
}
public static void main(String[] args) {
Stack<Integer> test = new Stack<Integer>();
test.push(1);
test.push(2);
test.push(3);
test.push(4);
test.push(5);
reverse(test);
while (!test.isEmpty()) {
System.out.println(test.pop());
}
}
}