Leetcode 232 Solution

This article provides solution to leetcode question 232 (implement-queue-using-stacks)
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https://leetcode.com/problems/implement-queue-using-stacks

Solution

class Queue {
    stack<int> s1;
    stack<int> s2;

    void adjust()
    {
        while (s1.empty() == false)
        {
            s2.push(s1.top());
            s1.pop();
        }
    }

public:
    // Push element x to the back of queue.
    void push(int x) {
        s1.push(x);
    }

    // Removes the element from in front of queue.
    void pop(void) {
        if (s2.empty())
            adjust();
        s2.pop();
    }

    // Get the front element.
    int peek(void) {
        if (s2.empty())
            adjust();
        return s2.top();
    }

    // Return whether the queue is empty.
    bool empty(void) {
        return s1.empty() && s2.empty();
    }
};