有没有大佬解答一下这段代码为什么RE了呢？

#include<bits/stdc++.h>
using namespace std;
struct node{
    int data;
    node *next;
    node()
    {
        next = nullptr;
    }
};
node l[305];
int main()
{
    int n, m;
    cin >> n >> m;
    for(int i = 1; i <= n; i++)
    {
        l[i].data = i;
        l[i].next = &l[i + 1];
    }
    l[n].next = &l[1];

    node *pre = &l[n];
    node *cur = &l[1];

    int bs = 1;
    int r = n;
    while(r != 1)
    {
        if(bs == m)
        {
            cur = cur->next;
            pre->next = cur;
            bs = 1;
            r--;
        }
        else
        {
            pre = cur;
            cur = cur->next;
            bs ++;
        }
    }

    cout << cur->data << endl;

    return 0;
}