图的存储方式、DFS、BFS

// Problem: ${json.name}
// Contest: ${json.group}
// URL: ${json.url}
// Memory Limit: ${json.memoryLimit} MB
// Time Limit: ${json.timeLimit} ms
// More thought is needed

#include <bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
vector<int> fa[60];
void dfs(int n) {//深度遍历
  cout << n << " ";
  for (auto& i : fa[n]) {
    dfs(i);
  }
}
void bfs(int n) {//广度遍历
  queue<int> qe;//尾进头出
  qe.push(n);
  while (qe.size()) {
    int x = qe.front();//一边压入一边输出
    qe.pop();
    cout << x << " ";
    for (auto& i : fa[x]) qe.push(i);
  }
}
void solve() {
  int n;
  cin >> n;
  for (int i = 2; i <= n; i++) {
    int fa_i;
    cin >> fa_i;
    fa[fa_i].push_back(i);//邻接表存储法
  }
  dfs(1);
  cout << endl;
  bfs(1);
}

signed main() {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  solve();
  return 0;
}

// Problem: ${json.name}
// Contest: ${json.group}
// URL: ${json.url}
// Memory Limit: ${json.memoryLimit} MB
// Time Limit: ${json.timeLimit} ms
// More thought is needed

#include <bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
const int N = 1e5 + 9;
vector<int> v[N];
bitset<N> vis;//标记数组
void find_v(int n) {
  vis[n] = true;
  for (auto& i : v[n]) {//dfs
    if (vis[i]) {//如果标记过了,则跳过,回环
      continue;
    }
    find_v(i);
  }
}
void solve() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int k, j;
    cin >> k >> j;
    if (k != j) v[k].push_back(j);//剔除自回环
  }
  find_v(1);
  for (int i = 1; i <= n; i++) {
    if (vis[i]) cout << i << " ";//全遍历,验证标记
  }
}

signed main() {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  solve();
  return 0;
}

// Problem: ${json.name}
// Contest: ${json.group}
// URL: ${json.url}
// Memory Limit: ${json.memoryLimit} MB
// Time Limit: ${json.timeLimit} ms
// More thought is needed

#include <bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
vector<int> res;
bitset<15> vis;//为什么是15呢
void arr(int n, int len) {
  if (len == n) {
    for (auto& i : res) {
      cout << i << " ";
    }
    cout << endl;
    return;
  }
  for (int i = 1; i <= n; i++) {
    if (vis[i]) continue;//剪枝
    vis[i] = true;//标记
    res.push_back(i);
    len++;
    arr(n, len);
    vis[i] = false;//回溯
    res.pop_back();
    len--;
  }
}
void solve() {
  int n;
  cin >> n;
  arr(n, 0);
}

signed main() {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  solve();
  return 0;
}

有空再写