c语言链表删除重复的结点

C 语言链表删除重复的结点可以分为两种情况：删除所有重复结点和仅保留一个重复结点。

删除所有重复结点的代码如下：

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

struct ListNode* deleteDuplicates(struct ListNode* head) {
    if (head == NULL) {
        return NULL;
    }
    struct ListNode* dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    dummy->next = head;
    struct ListNode* pre = dummy;
    struct ListNode* cur = head;
    while (cur != NULL) {
        while (cur->next != NULL && cur->val == cur->next->val) {
            cur = cur->next;
        }
        if (pre->next == cur) {
            pre = cur;
        } else {
            pre->next = cur->next;
        }
        cur = cur->next;
    }
    return dummy->next;
}

仅保留一个重复结点的代码如下：

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

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

这两段代码都是通过遍历链表，找到重复结点并删除。第一段代码会删除所有重复结点，第二段代码会仅保留一个重复结点。