题解 | #用两个栈实现队列#
用两个栈实现队列
https://www.nowcoder.com/practice/54275ddae22f475981afa2244dd448c6
class Solution
{
public:
void push(int node) {
stack1.push(node);
}
int pop() {
if(stack2.empty())
{
while(!stack1.empty())
{
int temp = stack1.top();
stack2.push(temp);
stack1.pop();
}
}
int res = 0;
res = stack2.top();
stack2.pop();
return res;
}
private:
stack<int> stack1;
stack<int> stack2;
};
另一种写法：
class Solution
{
public:
void push(int node) {
stack1.push(node);
}
int pop() {
//将第一个栈中内容弹出放入第二个栈中
while(!stack1.empty())
{
stack2.push(stack1.top());
stack1.pop();
}
//第二个栈栈顶就是最先进来的元素，即队首
int res = stack2.top();
stack2.pop();
//再将第二个栈的元素放回第一个栈
while(!stack2.empty())
{
stack1.push(stack2.top());
stack2.pop();
}
return res;
}
private:
stack<int> stack1;
stack<int> stack2;
};
