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| 1 | +#include <stdio.h> |
| 2 | +#include <stdlib.h> |
| 3 | + |
| 4 | +struct ListNode { |
| 5 | + int val; |
| 6 | + struct ListNode *next; |
| 7 | +}; |
| 8 | + |
| 9 | +struct ListNode* deleteDuplicates(struct ListNode* head) { |
| 10 | + if (head == NULL || head->next == NULL) return head; |
| 11 | + |
| 12 | + struct ListNode *dummy = malloc(sizeof(struct ListNode)); |
| 13 | + dummy->val = 0; |
| 14 | + dummy->next = head; |
| 15 | + struct ListNode *pre = dummy; |
| 16 | + struct ListNode *p = dummy->next; |
| 17 | + struct ListNode *q = dummy->next->next; |
| 18 | + |
| 19 | + while (p && q) { |
| 20 | + if (p->val == q->val) { |
| 21 | + pre->next = q->next; |
| 22 | + p = p->next; |
| 23 | + q = q->next; |
| 24 | + } |
| 25 | + else { |
| 26 | + if (pre->next == q) { |
| 27 | + p = p->next; |
| 28 | + q = q->next; |
| 29 | + } |
| 30 | + else { |
| 31 | + pre = pre->next; |
| 32 | + p = p->next; |
| 33 | + q = q->next; |
| 34 | + } |
| 35 | + } |
| 36 | + } |
| 37 | + |
| 38 | + struct ListNode *new_head = dummy->next; |
| 39 | + free(dummy); |
| 40 | + |
| 41 | + return new_head; |
| 42 | +} |
| 43 | + |
| 44 | +struct ListNode * buildList(int *nums, int numsSize) { |
| 45 | + if (numsSize == 0) return NULL; |
| 46 | + |
| 47 | + struct ListNode *dummy = malloc(sizeof(struct ListNode)); |
| 48 | + dummy->val = 0; |
| 49 | + struct ListNode *p = dummy; |
| 50 | + for (int i = 0; i < numsSize; i++) { |
| 51 | + p->next = malloc(sizeof(struct ListNode)); |
| 52 | + p->next->val = nums[i]; |
| 53 | + p = p->next; |
| 54 | + } |
| 55 | + p->next = NULL; |
| 56 | + |
| 57 | + p = dummy->next; |
| 58 | + free(dummy); |
| 59 | + |
| 60 | + return p; |
| 61 | +} |
| 62 | + |
| 63 | +int main() { |
| 64 | + |
| 65 | + int nums[] = { 1, 2, 2, 2, 3, 3 }; |
| 66 | + struct ListNode *head = buildList(nums, sizeof(nums) / sizeof(nums[0])); |
| 67 | + struct ListNode *p = head; |
| 68 | + while (p) { |
| 69 | + printf("%d->", p->val); |
| 70 | + p = p->next; |
| 71 | + } |
| 72 | + printf("NIL\n"); |
| 73 | + |
| 74 | + struct ListNode *new_head = deleteDuplicates(head); |
| 75 | + |
| 76 | + p = new_head; |
| 77 | + while (p) { |
| 78 | + printf("%d->", p->val); |
| 79 | + p = p->next; |
| 80 | + } |
| 81 | + printf("NIL\n"); |
| 82 | + |
| 83 | + return 0; |
| 84 | +} |
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