- 用两个栈来实现一个队列,完成队列的Push和Pop操作。 队列中的元素为int类型。完成如下代码:
import java.util.Stack;
public class Solution {
Stack<Integer> stack1 = new Stack<Integer>();
Stack<Integer> stack2 = new Stack<Integer>();
public void push(int node) {
}
public int pop() {
}
}
- 思路:push操作直接压入栈stack1,pop操作借助stack2,取出最先入栈的元素,再重构stack1
- 代码:
public class Solution {
Stack<Integer> stack1 = new Stack<Integer>();
Stack<Integer> stack2 = new Stack<Integer>();
public void push(int node) {
stack1.push(node);
}
public int pop() {
while (!stack1.isEmpty()){
stack2.push(stack1.pop());
}
int first=stack2.pop();
while (!stack2.isEmpty()){
stack1.push(stack2.pop());
}
return first;
}