C语言双向链表写法 （虚拟头尾节点）

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

typedef struct _List {
	struct _List *pr;
	int num;
	struct _List *ne;
} List; //节点结构体

int n;
List *head, *tail; //头节点、尾节点指针

void init() {
	head = (List*)malloc(sizeof(List));
	tail = (List*)malloc(sizeof(List));
	head -> pr = NULL;
	head -> ne = tail;
	tail -> pr = head;
	tail -> ne = NULL;
} //链表初始化

void insert_to_tail(int x) {
	List *temp = (List*)malloc(sizeof(List));
	temp -> pr = tail -> pr;
	temp -> num = x;
	temp -> ne = tail;
	tail -> pr -> ne = temp;
	tail -> pr = temp;
} //在尾部新增节点

void earse(List *temp) {
	temp -> pr -> ne = temp -> ne;
	temp -> ne -> pr = temp -> pr;
} //删除节点

int main()
{
	scanf("%d", &n);
	init();
	for(int i = 1; i <= n; i++) {
		insert_to_tail(i);
	}
	int rec = 1, flag = 1; //rec计数，flag标记方向
	List *temp = head -> ne;
	while(n) {
        if(n == 2 && rec == 1) { //剩下两个人报1结束
			printf("\n%d\n", temp -> num);
			break;
		}
		if(rec == 3) { //踢人
			printf("%d ", temp -> num);
			earse(temp);
			n--;
		}
		if(flag && temp -> ne == tail) flag = 0;
		if(!flag && temp -> pr == head) flag = 1; //转换方向
		flag ? temp = temp -> ne : temp = temp -> pr; //下一个人
		rec = rec % 3 + 1; //报数
	}
	return 0;	
}