约瑟夫问题

题目连接：约瑟夫问题 

#include <iostream>
#include <cstring>
using namespace std;

struct node{
    int id;
    node* pre;
    node* nxt;
};

node* p;
int n, m;

bool in(){
    delete p;
    cin >> n >> m;
    if(n == 0) return 0;
    node* head = new node({1, NULL, NULL});
    p = head;
    for(int i = 2; i <= n; ++i){
        p->nxt = new node({i, p, NULL});
        p = p->nxt;
    }
    // p->id == n
    p->nxt = head;
    head->pre = p;
    p = head;
    return 1;
}

int main()
{
    while(in()){
        while(p->nxt != p){
            for(int i = 1; i < m; ++i) p = p->nxt;
            node* pp = p->pre;
            pp->nxt = p->nxt;
            p->nxt->pre = pp;
            delete p;
            p = pp->nxt;
        }
        cout << p->id << endl;
    }
    system("pause");
    return 0;
}