s1.cpp

// OJ: https://leetcode.com/problems/design-circular-queue/
// Author: github.com/lzl124631x
// Time: O(1)
// Space: O(K)
class MyCircularQueue {
private:
    vector<int> v;
    int start = 0, len = 0;
public:
    MyCircularQueue(int k): v(k) {}
    bool enQueue(int value) {
        if (isFull()) return false;
        v[(start + len++) % v.size()] = value;
        return true;
    }
    bool deQueue() {
        if (isEmpty()) return false;
        start = (start + 1) % v.size();
        --len;
        return true;
    }
    int Front() {
        if (isEmpty()) return -1;
        return v[start];
    }
    int Rear() {
        if (isEmpty()) return -1;
        return v[(start + len - 1) % v.size()];
    }
    bool isEmpty() {
        return !len;
    }
    bool isFull() {
        return len == v.size();
    }
};