约瑟夫环问题

青旅半醒 2022-03-27 14:54 287阅读 0赞

/* 约瑟夫环问题(Josephus)
      用户输入M,N值，从1至N开始顺序循环数数，每数到M输出该数值，直至全部输出。写出C程序。（约瑟夫环问题 Josephus）
     */
     #include <stdio.h>
     #include <stdlib.h>
     
     // 链表节点
     typedef struct _RingNode
     {
         int pos;  // 位置
         struct _RingNode *next;
     }RingNode, *RingNodePtr;
     
     // 创建约瑟夫环，pHead:链表头指针，count:链表元素个数
     void CreateRing(RingNodePtr pHead, int count)
     {
         RingNodePtr pCurr = NULL, pPrev = NULL;
         int i = 1;
         pPrev = pHead;
         while(--count > 0)
         {
             pCurr = (RingNodePtr)malloc(sizeof(RingNode));
             i++;
             pCurr->pos = i;
             pPrev->next = pCurr;
             pPrev = pCurr;
         }
         pCurr->next = pHead;  // 构成环状链表
     }
     
     void PrintRing(RingNodePtr pHead)
     {
         RingNodePtr pCurr;
         printf("%d", pHead->pos);
         pCurr = pHead->next;
         while(pCurr != NULL)
         {
             if(pCurr->pos == 1)
                 break;
             printf("\n%d", pCurr->pos);
             pCurr = pCurr->next;
         }
     }
     
     void KickFromRing(RingNodePtr pHead, int m)
     {
         RingNodePtr pCurr, pPrev;
         int i = 1;    // 计数
         pCurr = pPrev = pHead;
         while(pCurr != NULL)
         {
             if (i == m)
             {
                 // 踢出环
                 printf("\n%d", pCurr->pos);    // 显示出圈循序
                 pPrev->next = pCurr->next;
                 free(pCurr);
                 pCurr = pPrev->next;
                 i = 1;
             }
             pPrev = pCurr;
             pCurr = pCurr->next;
             if (pPrev == pCurr)
             {
                 // 最后一个
                 printf("\n%d", pCurr->pos);    // 显示出圈循序
                 free(pCurr);
                 break;
             }
             i++;
         }
     }
     
     int main()
     {
         int m = 0, n = 0;
         RingNodePtr pHead = NULL;
         printf("---------------Josephus Ring---------------\n");
         printf("N(person count) = ");
         scanf("%d", &n);
         printf("M(out number) = ");
         scanf("%d", &m);
         if(n <= 0 || m <= 0)
         {
             printf("Input Error\n");
             system("pause");
             return 0;
         }
         // 建立链表
         pHead = (RingNodePtr)malloc(sizeof(RingNode));
         pHead->pos = 1;
         pHead->next = NULL;
         CreateRing(pHead, n);
     #ifdef _DEBUG
         PrintRing(pHead);
     #endif
     
         // 开始出圈
         printf("\nKick Order: ");
         KickFromRing(pHead, m);    
         printf("\n");
         system("pause");
         return 0;
     }