挑战程序设计竞赛8.2有根树的表达（个人注释代码）

本人大一初学，各位高手轻喷，欢迎交流。

#include<stdio.h>
#include<cmath>
#include<algorithm>
#include<vector>
#include<stack>
#include<map>
#include<list>
#include<ctime>
#include<iostream>
#include<cctype>
#include<iomanip>
constexpr auto maxn = 100005;
#define nil -1
using namespace std;
struct NODE
{
    int p, l, r;
};
NODE T[maxn];
int n, D[maxn];
void print(int u)
{
    int i, c;
    cout << "node " << u << ":";
    cout << "parent = " << T[u].p << ", ";
    cout << "depth = " << D[u] << ", ";
    if (T[u].p == nil)
        cout << "root, ";
    else if (T[u].l == nil)
        cout << "leaf, ";
    else
        cout << "internal node, ";
    cout << "[";
    for (int i = 0, c = T[u].l; c != nil; i++, c = T[c].r)//从当前结点的左结点开始依次遍历左结点的右兄弟结点，直到为空
    {
        if (i)
            cout << ",";
        cout << c;
    }
    cout << "]" << endl;
}
int depth(int u, int p)
{
    D[u] = p;
    if (T[u].r != nil)
        depth(T[u].r, p);
    if (T[u].l != nil)
        depth(T[u].l , p+1);
    return 1;
}
int main()
{
    int i, j, d, v, c, l, r;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        T[i].p = T[i].r =T[i].l= nil;
    }
    for (int i = 0; i < n; i++)
    {
        cin >> v >> d;
        for (j = 0; j < d; j++)
        {
            cin >> c;
            if (j == 0)//先输入左结点
                T[v].l = c;
            else//再输入当前结点的左结点的兄弟结点
                T[l].r = c;
            l = c;//把l替换成左结点的兄弟结点
            T[c].p = v;//正在录入的结点是父节点
        }
    }
    for (int i = 0; i < n; i++)//找到父节点
    {
        if (T[i].p == nil)r = i;
    }
    depth(r, 0);//从父节点开始往下计算左结点的深度，并往右兄弟结点依次赋值
    for (i = 0; i < n; i++)print(i);
    return 0;