用C语言删除单链表中重复结点，重复结点只保留一个，head是单链表首结点指针

以下是用C语言删除单链表中重复结点，重复结点只保留一个的代码：

#include <stdio.h>
#include <stdlib.h>

struct ListNode {
    int val;
    struct ListNode *next;
};

struct ListNode* deleteDuplicates(struct ListNode* head) {
    if (head == NULL || head->next == NULL) {
        return head;
    }
    struct ListNode *p = head;
    while (p->next != NULL) {
        if (p->val == p->next->val) {
            struct ListNode *temp = p->next;
            p->next = temp->next;
            free(temp);
        } else {
            p = p->next;
        }
    }
    return head;
}

int main() {
    struct ListNode *head = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->val = 1;
    head->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->val = 1;
    head->next->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->next->val = 2;
    head->next->next->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->next->next->val = 3;
    head->next->next->next->next = NULL;
    head = deleteDuplicates(head);
    while (head != NULL) {
        printf("%d ", head->val);
        head = head->next;
    }
    printf("\n");
    return 0;
}

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