题解 | #【模板】队列#

#include <stdio.h>
#include <string.h>
#define N 1000000

typedef struct Queue {
    int front;
    int rear;
    int data[N];
} Queue;

void QueueInit(Queue* q) {
    q->front = 0;
    q->rear = 0;
}

void QueuePush(Queue* q, int x) {
    q->data[q->rear] = x;
    q->rear = q->rear+1; // Ensure circular behavior
}

void QueuePop(Queue* q) {
    if (q->front == q->rear) {
        printf("error\n");
        return;
    }
    printf("%d\n",q->data[q->front]);
    q->front+=1;
}

void QueueFront(Queue* q) {
    if (q->front == q->rear) {
        printf("error\n");
        return;
    }
    printf("%d\n", q->data[q->front]);
}

int main() {
    Queue s;
    char str[6];
    int b, n;
    QueueInit(&s);
    scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        scanf("%s %d",str,&b);
        if (strcmp(str, "push") == 0) {
            QueuePush(&s, b);
        } else if (strcmp(str, "pop") == 0) {
            QueuePop(&s);
        } else if (strcmp(str, "front") == 0) {
            QueueFront(&s);
        }
    }
    return 0;
}