最标准的C语言题解啦，可能以后都不会在这个网站登录啦，感谢C语言网陪伴了我一个寒假，收获颇丰

#include<stdio.h>

#include<stdlib.h>

 struct ListNode {

int val;

struct ListNode* next;

};

 int main() {

int n;

scanf_s("%d", &n);

struct ListNode* head = NULL, * head2 = head;

for(int i = 0 ;i < n; i++){

struct ListNode* t = (struct ListNode*)malloc(sizeof(struct ListNode));

t->val = i + 1;

t->next = NULL;

if (!head) {

head = t;

head2 = head;

  }

else {

head->next = t;

head = head->next;

}

}

head->next = head2;

while (head2->next != head2) {

struct ListNode* t = head2->next;

head2 = head2->next->next;

t->next = head2->next;

free(head2);

head2 = t->next;

}

if (head != NULL) {

printf("%d", head2->val);

}

else {

printf("出错了！");

}

return 0;

 }