题解 | #环形链表的约瑟夫问题#

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param n int整型 
 * @param m int整型 
 * @return int整型
 */
typedef struct ListNode ListNode;
//创建新节点
ListNode* BuyNode(int x)
{
    ListNode* newnode = (ListNode*)malloc(sizeof(ListNode));
    newnode->val = x;
    newnode->next = NULL;

    return newnode;
}
//循环链表的创建
ListNode* List(int n)
{
    ListNode* phead = BuyNode(1);
    ListNode* ptail = phead;
    for(int i = 2; i <= n; i++)
    {
        ptail->next = BuyNode(i);
        ptail = ptail->next;
    }
    ptail->next = phead;
    return phead;
}

int ysf(int n, int m ) {
    // write code here
    //如果m为1，直接返回1
    if(m == 1)
    {
        return 1;
    }
    ListNode* phead = List(n);
    ListNode* pcur = phead;
    ListNode* prev = NULL;
    //定义count记录报数
    int count = 1;
    while(pcur->next != pcur)
    {
        if(count == m)
        {
            prev->next = pcur->next;
            free(pcur);
            pcur = prev->next;
            count = 1;
        }
        else 
        {
            prev = pcur;
            pcur = pcur->next;
            count++;

        }
    }
    return pcur->val;
    
}