【C语言】循环链表解决约瑟夫环问题

好玩的约瑟夫环：有M个人，编号分别为1到M，玩约瑟夫环游戏，最初时按编号顺序排成队列；每遍游戏开始时，有一个正整数报数密码N，队列中人依次围坐成一圈，从队首的人开始报数，报到N的人出列，然后再从出列的下一人开始重新报数，报到N的人出列；重复这一过程，直至所有人出列，完成一遍游戏，所有出列的人形成新队列；游戏可能玩很多遍，每遍有新报数密码。求若干遍游戏完成后队列次序。题目输入包括若干个正整数（至少1个），第一个正整数为玩游戏人数M，后续每个正整数为每遍游戏报数密码，报数密码可能为1，题目要求按出队列顺序输出他们的编号。

输入样例:

10   3   5    2

输出样例:

   4   6   5   2   9   1   3   7   8  10

代码如下： 

#include 
#include 

struct Node {
    int data;
    struct Node *next;
};
//createNew
struct Node *createNew()
{
    struct Node *p;
    p =  (struct Node *)malloc(sizeof(struct Node));
    p -> next = NULL;
    return p;

};

//build创建循环链表
void build (struct Node **pp, int m) {
    struct Node *phead, *pnew, *pold;
    phead = *pp;
    pold = phead;
    int i;
    for(i = 1; i <= m; i++) {
        pnew = createNew();
        pnew -> data = i;
        pold -> next = pnew;
        pold = pold -> next;
    }
    pold -> next = phead -> next;
}


//append添加人数
void append(struct Node **pp1, struct Node **pp2, int n) {
    struct Node *phead1, *phead2, *pold, *pafter, *pnext;
    phead1 = *pp1;
    phead2 = *pp2;
    pold = phead1 -> next;
    pafter = pold -> next;
    pnext = phead2;

    while(phead1 -> next){

        if(n >= 3) {
            for(int i = 0; i < n - 2; i++) {
                pold = pold -> next;
                pafter = pold -> next;
            }
        }
        else if(n == 2) {
            pafter = pold -> next;
        }
        else if(n == 1) {
            pold = phead1;
            pafter = pold -> next;
        }

        //phead2未存储数据
        if(!phead2 -> next) {
            phead2 -> next = pafter;
            pnext = pnext -> next;
        }

//printf("pnext = %dn",pnext -> data);
        else {
            pnext -> next = pafter;
            pnext = pnext -> next;
        }

        pold -> next = pafter -> next;
        pold = pold -> next;

//printf("pnext->next = %dn",pnext -> data);
//printf("pold = %dn",pold -> data);

        //只剩下一个人n >= 2跳出循环的条件
        if(pold == pold -> next) {
            pnext = pold;
            pnext -> next = NULL;
            break;
        }
        //n == 1跳出循环的条件
        if(n == 1) {
            if(pafter -> next -> data == phead2 -> next -> data) {
                pafter -> next = NULL;
                break;
            }
        }
    }
}

//print
void print(struct Node *p, int m)
{
    for(int i = 0; i < m; i++) {
        printf("%4d",p -> next -> data);
        p = p -> next;
    }

}

void repeat(struct Node **pp) {
    struct Node *phead, *pnext;
    phead = *pp;
    pnext = phead -> next;
    while(pnext -> next) {
        pnext = pnext -> next;
    }
    pnext -> next = phead -> next;

}


//destroy
void destroy(struct Node *p)
{
    struct Node *pnext;
    while(p) {
        pnext = p -> next;
        free(p);
        p = pnext;
 }
 //printf("destroyed!");
}


int main()
{
     //新建两个链表的头节点
    struct Node *phead1, *phead2;
    phead1 = createNew();
    phead2 = createNew();

    //输入人数
    int m;
    scanf("%d",&m);

    //创建循环链表
    build(&phead1,m);

    //第一次游戏
    int x;
    scanf("%d",&x);
    append(&phead1,&phead2,x);

    //循环游戏
    while(getchar() == ' ') {
        phead1 = phead2;
        repeat(&phead1);
        phead2 = createNew();
        scanf("%d",&x);
        append(&phead1,&phead2,x);

    }

    //打印
    print(phead2,m);

    //销毁
    destroy(phead2);

    return 0;
}