剑指offer 用两个栈实现队列

Posted 2020-12-31 一条图图犬

class Solution
{
public:
    void push(int node) {
        stack1.push(node);
    }

    int pop() {
        if(stack1.empty() && stack2.empty()){
            return -1;
        }
        if(!stack2.empty()){
            stack2.pop();
        }
        else{
            while(!stack1.empty()){
                stack2.push(stack1.top());
                stack1.pop();
            }
        }
        return stack2.top();
    }

private:
    stack<int> stack1;
    stack<int> stack2;
};