#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
int m, n;
struct Node{
	int data;
	Node *next;
} *head, *p, *tail, *temp;
void sc(Node *head,int m,int n){
    Node *r,*p;
    r=head;
    p=r->next;
    int t=0,k=0;
    while(t!=m-1){
        k++;
        if(k==n){
            r->next=p->next;
            //cout<<p->data<<endl;
            t++;
            k=0;
        }
        else{
            r=p;
        }
        p=p->next;
    }
    cout<<p->data<<endl;
}
int main(){
    while(1){
        cin>>m>>n;
        if(n==0||m==0)return 0;
        head = new Node;
        head -> next = NULL;
        tail = head;
        for(int i = 1; i <= m; i++){
            p = new Node;
            p -> data = i;
            p -> next = NULL;
            tail -> next = p;
            tail = p;
        }
        p = head -> next;
        tail -> next = head -> next;
        sc(head,m,n);
    }
	return 0;
}

上面的是对的，下面的是错的

#include<iostream>
#include<cstdio>
#include<cstdlib>
using namespace std;
int m, n;
struct Node{
	int data;
	Node *next;
} *head, *p, *tail, *temp;
void sc(){
    for(int i = 1; i < m; i++){
            for(int j = 1; j < n - 1; j++){
                p = p -> next;
            }
            temp = p -> next;
            p -> next = temp -> next;
            p = p -> next;
            free(temp);
        }
    cout<<p->data<<endl;
    return ;
}
int main(){
    while(1){
        cin>>m>>n;
        if(n==0||m==0)return 0;
        head = new Node;
        head -> next = NULL;
        tail = head;
        for(int i = 1; i <= m; i++){
            p = new Node;
            p -> data = i;
            p -> next = NULL;
            tail -> next = p;
            tail = p;
        }
        p = head -> next;
        tail -> next = head -> next;
        sc();
    }
	return 0;
}

问为什么 原题http://noi.openjudge.cn/ch0302/1748/