删除队列中的重复元素的C语言算法

在 C 语言中，可以使用类似 Python 中的哈希表实现来删除队列中的重复元素。以下是一个简单的示例：

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define MAX_SIZE 100

struct queue {
    int data[MAX_SIZE];
    int front, rear;
};

struct hash_table {
    int *keys;
    bool *values;
    int size;
};

struct queue *create_queue() {
    struct queue *q = malloc(sizeof(struct queue));
    q->front = -1;
    q->rear = -1;
    return q;
}

struct hash_table *create_hash_table(int size) {
    struct hash_table *table = malloc(sizeof(struct hash_table));
    table->keys = malloc(size * sizeof(int));
    table->values = malloc(size * sizeof(bool));
    table->size = size;
    for (int i = 0; i < size; i++) {
        table->keys[i] = 0;
        table->values[i] = false;
    }
    return table;
}

void enqueue(struct queue *q, int value) {
    if (q->rear == MAX_SIZE - 1) {
        printf("Queue overflow\n");
        return;
    }
    if (q->front == -1) {
        q->front = 0;
    }
    q->rear++;
    q->data[q->rear] = value;
}

int dequeue(struct queue *q) {
    if (q->front == -1 || q->front > q->rear) {
        printf("Queue underflow\n");
        return -1;
    }
    int value = q->data[q->front];
    q->front++;
    return value;
}

bool is_empty(struct queue *q) {
    return q->front == -1 || q->front > q->rear;
}

bool is_full(struct queue *q) {
    return q->rear == MAX_SIZE - 1;
}

void delete_queue(struct queue *q) {
    free(q);
}

int hash(int key, int size) {
    return key % size;
}

void insert(struct hash_table *table, int key) {
    int index = hash(key, table->size);
    while (table->values[index] && table->keys[index] != key) {
        index = hash(index + 1, table->size);
    }
    table->keys[index] = key;
    table->values[index] = true;
}

bool search(struct hash_table *table, int key) {
    int index = hash(key, table->size);
    while (table->values[index]) {
        if (table->keys[index] == key) {
            return true;
        }
        index = hash(index + 1, table->size);
    }
    return false;
}

void remove_duplicates(struct queue *q) {
    struct hash_table *table = create_hash_table(MAX_SIZE);
    struct queue *new_q = create_queue();
    while (!is_empty(q)) {
        int value = dequeue(q);
        if (!search(table, value)) {
            insert(table, value);
            enqueue(new_q, value);
        }
    }
    while (!is_empty(new_q)) {
        int value = dequeue(new_q);
        enqueue(q, value);
    }
    delete_queue(new_q);
    free(table->keys);
    free(table->values);
    free(table);
}

int main() {
    struct queue *q = create_queue();
    enqueue(q, 1);
    enqueue(q, 2);
    enqueue(q, 3);
    enqueue(q, 2);
    enqueue(q, 4);
    remove_duplicates(q);
    while (!is_empty(q)) {
        printf("%d ", dequeue(q));
    }
    printf("\n");
    delete_queue(q);
    return 0;
}

这个程序定义了两个数据结构：队列和哈希表。其中哈希表用于判断队列中的元素是否已经出现过。具体实现细节可以参考代码注释。