leetcode 622. Design Circular Queue | 622. 设计循环队列（Ring Buffer）

以你之姓@ 2022-09-15 06:00 176阅读 0赞

## 题目 ##

[https://leetcode.com/problems/design-circular-queue/][https_leetcode.com_problems_design-circular-queue]  
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## 题解 ##

Ring Buffer 的实现，rear 指向新插入的位置，front 指向最旧的位置，注意本题的 front 和 rear 方法是 peek 而已，是不 delete 元素的。  
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class MyCircularQueue { 
        int[] queue;
        int N;
        int front = 0; // 下一个有值的位置
        int rear = 0; // 下一个空位置
        int size = 0; // 简化判空判满逻辑
    
        public MyCircularQueue(int k) { 
            queue = new int[k];
            N = k;
        }
    
        public boolean enQueue(int value) { 
            if (size == queue.length) return false;
            queue[rear++] = value;
            rear %= N;
            size++;
            return true;
        }
    
        public boolean deQueue() { 
            if (size == 0) return false;
            front++;
            front %= N;
            size--;
            return true;
        }
    
        public int Front() {  // peek front
            if (size == 0) return -1;
            return queue[front];
        }
    
        public int Rear() {  // peek rear
            if (size == 0) return -1;
            return queue[(rear - 1 + N) % N];
        }
    
        public boolean isEmpty() { 
            return size == 0;
        }
    
        public boolean isFull() { 
            return size == N;
        }
    }
    
    /** * Your MyCircularQueue object will be instantiated and called as such: * MyCircularQueue obj = new MyCircularQueue(k); * boolean param_1 = obj.enQueue(value); * boolean param_2 = obj.deQueue(); * int param_3 = obj.Front(); * int param_4 = obj.Rear(); * boolean param_5 = obj.isEmpty(); * boolean param_6 = obj.isFull(); */

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]

[https_leetcode.com_problems_design-circular-queue]: https://leetcode.com/problems/design-circular-queue/
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[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_12_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/777e8cb017da464992e8ddd70876a423.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220828/9ed47a1627bb4bf1a7f865d6b3234e06.png