有人能帮我把这个程序最后的删除函数解释一下吗?

#include<iostream>
using namespace std;
struct Node
{
    int data;
    Node *next;
};
Node *CreateList(Node *L,int &n);
void Joseph(Node *L,int n,int m);
Node *DeleteList(Node *&L,int i,Node *q);
int main()
{
    Node *L;
    L=NULL;
    int n,m;
    cout<<"请输入人数N:";
    cin>>n;
    if(n<1) {cout<<"请输入正整数!";}
    else
    {
        cout<<"请输入密码M:";
        cin>>m;
        if(m<1) {cout<<"请输入正整数!";}
        else
        {
            L=CreateList(L,n);
            Joseph(L,n,m);
        }
    }
    system("pause");
    return 0;
}
Node *CreateList(Node *L,int &n)
{
    Node *q;
    for(int i=1;i<=n;i++)
    {
        Node *p;
        p=new Node;
        p->data=i;
        p->next=NULL;
        if(i==1)
            L=q=p;
        else
        {
            q->next=p;
            q=q->next;
        }
    }
    q->next=L;
    if(L!=NULL)
        return(L);
    else
        cout<<"尾指针异常!"<<endl;
}
void Joseph(Node *L,int n,int m)
{
    cout<<"\n出列顺序:\n";
    for(int i=1;i<n;i++)
    {
        Node *q=new Node;
        q=DeleteList(L,m,q);
        cout<<"号数:"<<q->data<<endl;
        delete(q);
    }
    cout<<"号数:"<<L->data<<endl;
    delete L;
}
Node *DeleteList(Node *&L,int i,Node *q)
{
    Node *p,*m;
    p=L;
    if(i==1)
    {
        m=p->next;
        while (m->next!=L)
            m=m->next;
        m->next=p->next;
        q=L;
        L=m->next;
        return q;
    }
    else
    {
        int j=1;
        while(j<i-1)
        {
            p=p->next;
            j++;
        }
        q=p->next;
        p->next=p->next->next;
        L=p->next;
        return(q);
    }
}