LeetCode_2/232-Implement-Queue-using-Stacks.cpp at main · argon2r/LeetCode_2 · GitHub

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class MyQueue {
public:
    stack<int> st;
    stack<int> helper;
    MyQueue() {

    }

    void push(int x) {
        st.push(x);
    }

    int pop() {
        while (!st.empty()){
            helper.push(st.top());
            st.pop();
        }
        int x = helper.top();
        helper.pop();
        while (!helper.empty()){
            st.push(helper.top());
            helper.pop();
        }
        return x;
    }

    int peek() {
        while (!st.empty()){
            helper.push(st.top());
            st.pop();
        }
        int x = helper.top();
        while (!helper.empty()){
            st.push(helper.top());
            helper.pop();
        }
        return x;
    }

    bool empty() {
        if(st.size() == 0) return true;
        else return false;
    }
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * MyQueue* obj = new MyQueue();
 * obj->push(x);
 * int param_2 = obj->pop();
 * int param_3 = obj->peek();
 * bool param_4 = obj->empty();
 */