Problem p03444 (C++)

Buggy submission (status: Time Limit Exceeded):
// #pragma GCC target("avx")  // CPU 処理並列化
// #pragma GCC optimize("O3")  // CPU 処理並列化
// #pragma GCC optimize("unroll-loops")  // 条件処理の呼び出しを減らす
// #define BEGIN_STACK_EXTEND(size) void * stack_extend_memory_ =
// malloc(size);void * stack_extend_origin_memory_;char *
// stack_extend_dummy_memory_ = (char*)alloca((1+(int)(((long
// long)stack_extend_memory_)&127))*16);*stack_extend_dummy_memory_ = 0;asm
// volatile("mov %%rsp, %%rbx\nmov %%rax,
// %%rsp":"=b"(stack_extend_origin_memory_):"a"((char*)stack_extend_memory_+(size)-1024));
// #define END_STACK_EXTEND asm volatile("mov %%rax,
// %%rsp"::"a"(stack_extend_origin_memory_));free(stack_extend_memory_);

#include <algorithm>
#include <bitset>
#include <cassert>
#include <complex>
#include <deque>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <time.h>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace std;
const long long mod = 1000000007;
const long long inf = mod * mod;
const long long d2 = (mod + 1) / 2;
const double EPS = 1e-9;
const double INF = 1e+10;
const double PI = acos(-1.0);
const int C_SIZE = 3100000;
const int UF_SIZE = 3100000;
namespace {
long long fact[C_SIZE];
long long finv[C_SIZE];
long long inv[C_SIZE];
inline long long Comb(int a, int b) {
  if (a < b || b < 0)
    return 0;
  return fact[a] * finv[b] % mod * finv[a - b] % mod;
}
void init_C(int n) {
  fact[0] = finv[0] = inv[1] = 1;
  for (int i = 2; i < n; i++) {
    inv[i] = (mod - (mod / i) * inv[mod % i] % mod) % mod;
  }
  for (int i = 1; i < n; i++) {
    fact[i] = fact[i - 1] * i % mod;
    finv[i] = finv[i - 1] * inv[i] % mod;
  }
}
long long pw(long long a, long long b) {
  if (a < 0LL)
    return 0;
  if (b < 0LL)
    return 0;
  long long ret = 1;
  while (b) {
    if (b % 2)
      ret = ret * a % mod;
    a = a * a % mod;
    b /= 2;
  }
  return ret;
}
long long pw_mod(long long a, long long b, long long M) {
  if (a < 0LL)
    return 0;
  if (b < 0LL)
    return 0;
  long long ret = 1;
  while (b) {
    if (b % 2)
      ret = ret * a % M;
    a = a * a % M;
    b /= 2;
  }
  return ret;
}
int pw_mod_int(int a, int b, int M) {
  if (a < 0)
    return 0;
  if (b < 0)
    return 0;
  int ret = 1;
  while (b) {
    if (b % 2)
      ret = (long long)ret * a % M;
    a = (long long)a * a % M;
    b /= 2;
  }
  return ret;
}
int ABS(int a) { return max(a, -a); }
long long ABS(long long a) { return max(a, -a); }
double ABS(double a) { return max(a, -a); }
int sig(double r) { return (r < -EPS) ? -1 : (r > +EPS) ? +1 : 0; }
int UF[UF_SIZE];
void init_UF(int n) {
  for (int i = 0; i < n; i++)
    UF[i] = -1;
}
int FIND(int a) {
  if (UF[a] < 0)
    return a;
  return UF[a] = FIND(UF[a]);
}
void UNION(int a, int b) {
  a = FIND(a);
  b = FIND(b);
  if (a == b)
    return;
  // if(UF[a]>UF[b])swap(a,b);
  UF[a] += UF[b];
  UF[b] = a;
}
} // namespace
// ここから編集しろ
vector<int> g[2100];
int par[2100];
int p[2100];
int v[2100];
int f[2100];
int dep[2100];
int rev[2100];
int col;
vector<int> ans;
int dfs(int a) {
  int ret = 0;
  int deg = 0;
  for (int i = 0; i < g[a].size(); i++) {
    int to = g[a][i];
    dep[to] = dep[a] + 1;
    if (~v[to])
      continue;
    int tmp = dfs(to);
    deg++;
    ret = max(ret, tmp);
  }
  ret = max(ret, deg);
  if (ret <= 1) {
    v[a] = col;
  }
  return ret;
}
int n;
void rot(int a) {
  ans.push_back(a);
  vector<pair<int, int>> tmp;
  while (~a) {
    tmp.push_back(make_pair(a, p[a]));
    a = par[a];
  }
  for (int i = 0; i < tmp.size(); i++) {
    p[tmp[(i + 1) % tmp.size()].first] = tmp[i].second;
  }
  // for(int i=0;i<n;i++){
  // 	printf("%d ",p[i]);
  // }printf("\n");
}
int dfs2(int a, int b, int c) {
  int ret = a;
  for (int i = 0; i < g[a].size(); i++) {
    if (v[g[a][i]] != b)
      continue;
    if (f[p[g[a][i]]] != 1 || p[g[a][i]] <= c) {
      ret = dfs2(g[a][i], b, c);
    }
  }
  return ret;
}
int main_(vector<int> A, vector<int> B) {
  int a = B.size();
  n = a;
  for (int i = 0; i < n; i++)
    g[i].clear();
  for (int i = 0; i < a - 1; i++) {
    int t;
    t = A[i];
    g[t].push_back(i + 1);
    par[i + 1] = t;
  }
  par[0] = -1;
  for (int i = 0; i < a; i++) {
    p[i] = B[i];
  }
  for (int i = 0; i < a; i++) {
    v[i] = -1;
  }
  int vis = 0;
  for (int i = 0; i < a; i++)
    f[i] = 0;
  while (vis < a) {
    // for(int i=0;i<a;i++)f[i]=0;
    // for(int i=0;i<a;i++)if(v[i]!=-1)f[i]=1;
    dfs(0);
    int rem = 0;
    for (int i = 0; i < a; i++) {
      if (v[i] == col) {
        vis++;
        rem++;
        f[p[i]] = 2;
      }
    }
    // for(int i=0;i<a;i++)printf("%d ",v[i]);printf("\n");

    while (rem) {
      int now = p[0];
      // if(f[now])break;
      if (v[now] == -1) {
        int TO = -1;
        for (int i = 0; i < a; i++) {
          if (f[p[i]] != 2)
            continue;
          // if(v[i]!=col)continue;
          bool ok = true;

          if (ok) {
            if (TO == -1 || dep[i] > dep[TO])
              TO = i;
          }
        }
        // printf("%d %d %d\n",col,now,i);
        if (~TO) {
          rot(TO);
          // f[now]=2;
        }
      } else {
        int at = dfs2(now, col, now);
        rot(at);
        f[now] = 1;
        rem--;
      }
    }
    col++;
  }
  // for(int i=0;i<n;i++){
  // 	if(p[i]!=i)return 0;
  // }
  // return 1;
  printf("%d\n", (int)ans.size());

  for (int i = 0; i < ans.size(); i++) {
    printf("%d\n", ans[i]);
  }
}
int main() {
  // while(1){
  vector<int> A;
  vector<int> B;

  int n;
  scanf("%d", &n);
  for (int i = 0; i < n - 1; i++) {
    int t;
    scanf("%d", &t);
    A.push_back(t);
  }
  for (int i = 0; i < n; i++) {
    int t;
    scanf("%d", &t);
    B.push_back(t);
  }
  main_(A, B);

  // int n=5;

  // for(int i=1;i<n;i++){
  // 	A.push_back(rand()%i);
  // }
  // for(int i=0;i<n;i++){
  // 	B.push_back(i);
  // }
  // random_shuffle(B.begin(),B.end());
  // if(main_(A,B)==0){
  // 	for(int i=0;i<A.size();i++)printf("%d ",A[i]);printf("\n");
  // 	for(int i=0;i<B.size();i++)printf("%d ",B[i]);printf("\n");

  // 	break;
  // }
  // }
}


Fixed submission:
// #pragma GCC target("avx")  // CPU 処理並列化
// #pragma GCC optimize("O3")  // CPU 処理並列化
// #pragma GCC optimize("unroll-loops")  // 条件処理の呼び出しを減らす
// #define BEGIN_STACK_EXTEND(size) void * stack_extend_memory_ =
// malloc(size);void * stack_extend_origin_memory_;char *
// stack_extend_dummy_memory_ = (char*)alloca((1+(int)(((long
// long)stack_extend_memory_)&127))*16);*stack_extend_dummy_memory_ = 0;asm
// volatile("mov %%rsp, %%rbx\nmov %%rax,
// %%rsp":"=b"(stack_extend_origin_memory_):"a"((char*)stack_extend_memory_+(size)-1024));
// #define END_STACK_EXTEND asm volatile("mov %%rax,
// %%rsp"::"a"(stack_extend_origin_memory_));free(stack_extend_memory_);

#include <algorithm>
#include <bitset>
#include <cassert>
#include <complex>
#include <deque>
#include <map>
#include <math.h>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <string>
#include <time.h>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace std;
const long long mod = 1000000007;
const long long inf = mod * mod;
const long long d2 = (mod + 1) / 2;
const double EPS = 1e-9;
const double INF = 1e+10;
const double PI = acos(-1.0);
const int C_SIZE = 3100000;
const int UF_SIZE = 3100000;
namespace {
long long fact[C_SIZE];
long long finv[C_SIZE];
long long inv[C_SIZE];
inline long long Comb(int a, int b) {
  if (a < b || b < 0)
    return 0;
  return fact[a] * finv[b] % mod * finv[a - b] % mod;
}
void init_C(int n) {
  fact[0] = finv[0] = inv[1] = 1;
  for (int i = 2; i < n; i++) {
    inv[i] = (mod - (mod / i) * inv[mod % i] % mod) % mod;
  }
  for (int i = 1; i < n; i++) {
    fact[i] = fact[i - 1] * i % mod;
    finv[i] = finv[i - 1] * inv[i] % mod;
  }
}
long long pw(long long a, long long b) {
  if (a < 0LL)
    return 0;
  if (b < 0LL)
    return 0;
  long long ret = 1;
  while (b) {
    if (b % 2)
      ret = ret * a % mod;
    a = a * a % mod;
    b /= 2;
  }
  return ret;
}
long long pw_mod(long long a, long long b, long long M) {
  if (a < 0LL)
    return 0;
  if (b < 0LL)
    return 0;
  long long ret = 1;
  while (b) {
    if (b % 2)
      ret = ret * a % M;
    a = a * a % M;
    b /= 2;
  }
  return ret;
}
int pw_mod_int(int a, int b, int M) {
  if (a < 0)
    return 0;
  if (b < 0)
    return 0;
  int ret = 1;
  while (b) {
    if (b % 2)
      ret = (long long)ret * a % M;
    a = (long long)a * a % M;
    b /= 2;
  }
  return ret;
}
int ABS(int a) { return max(a, -a); }
long long ABS(long long a) { return max(a, -a); }
double ABS(double a) { return max(a, -a); }
int sig(double r) { return (r < -EPS) ? -1 : (r > +EPS) ? +1 : 0; }
int UF[UF_SIZE];
void init_UF(int n) {
  for (int i = 0; i < n; i++)
    UF[i] = -1;
}
int FIND(int a) {
  if (UF[a] < 0)
    return a;
  return UF[a] = FIND(UF[a]);
}
void UNION(int a, int b) {
  a = FIND(a);
  b = FIND(b);
  if (a == b)
    return;
  // if(UF[a]>UF[b])swap(a,b);
  UF[a] += UF[b];
  UF[b] = a;
}
} // namespace
// ここから編集しろ
vector<int> g[2100];
int par[2100];
int p[2100];
int v[2100];
int f[2100];
int dep[2100];
int rev[2100];
int col;
vector<int> ans;
int dfs(int a) {
  int ret = 0;
  int deg = 0;
  for (int i = 0; i < g[a].size(); i++) {
    int to = g[a][i];
    dep[to] = dep[a] + 1;
    if (~v[to])
      continue;
    int tmp = dfs(to);
    deg++;
    ret = max(ret, tmp);
  }
  ret = max(ret, deg);
  if (ret <= 1) {
    v[a] = col;
  }
  return ret;
}
int n;
void rot(int a) {
  ans.push_back(a);
  vector<pair<int, int>> tmp;
  while (~a) {
    tmp.push_back(make_pair(a, p[a]));
    a = par[a];
  }
  for (int i = 0; i < tmp.size(); i++) {
    p[tmp[(i + 1) % tmp.size()].first] = tmp[i].second;
  }
  // for(int i=0;i<n;i++){
  // 	printf("%d ",p[i]);
  // }printf("\n");
}
int dfs2(int a, int b, int c) {
  int ret = a;
  for (int i = 0; i < g[a].size(); i++) {
    if (v[g[a][i]] != b)
      continue;
    if (f[p[g[a][i]]] != 1 || p[g[a][i]] <= c) {
      ret = dfs2(g[a][i], b, c);
    }
  }
  return ret;
}
int main_(vector<int> A, vector<int> B) {
  int a = B.size();
  n = a;
  for (int i = 0; i < n; i++)
    g[i].clear();
  for (int i = 0; i < a - 1; i++) {
    int t;
    t = A[i];
    g[t].push_back(i + 1);
    par[i + 1] = t;
  }
  par[0] = -1;
  for (int i = 0; i < a; i++) {
    p[i] = B[i];
  }
  for (int i = 0; i < a; i++) {
    v[i] = -1;
  }
  int vis = 0;
  for (int i = 0; i < a; i++)
    f[i] = 0;
  while (vis < a) {
    // for(int i=0;i<a;i++)f[i]=0;
    // for(int i=0;i<a;i++)if(v[i]!=-1)f[i]=1;
    dfs(0);
    int rem = 0;
    for (int i = 0; i < a; i++) {
      if (v[i] == col) {
        vis++;
        rem++;
        f[i] = 2;
      }
    }
    // for(int i=0;i<a;i++)printf("%d ",v[i]);printf("\n");

    while (rem) {
      int now = p[0];
      // if(f[now])break;
      if (v[now] == -1) {
        int TO = -1;
        for (int i = 0; i < a; i++) {
          if (f[p[i]] != 2)
            continue;
          // if(v[i]!=col)continue;
          bool ok = true;

          if (ok) {
            if (TO == -1 || dep[i] > dep[TO])
              TO = i;
          }
        }
        // printf("%d %d %d\n",col,now,i);
        if (~TO) {
          rot(TO);
          // f[now]=2;
        }
      } else {
        int at = dfs2(now, col, now);
        rot(at);
        f[now] = 1;
        rem--;
      }
    }
    col++;
  }
  // for(int i=0;i<n;i++){
  // 	if(p[i]!=i)return 0;
  // }
  // return 1;
  printf("%d\n", (int)ans.size());

  for (int i = 0; i < ans.size(); i++) {
    printf("%d\n", ans[i]);
  }
}
int main() {
  // while(1){
  vector<int> A;
  vector<int> B;

  int n;
  scanf("%d", &n);
  for (int i = 0; i < n - 1; i++) {
    int t;
    scanf("%d", &t);
    A.push_back(t);
  }
  for (int i = 0; i < n; i++) {
    int t;
    scanf("%d", &t);
    B.push_back(t);
  }
  main_(A, B);

  // int n=5;

  // for(int i=1;i<n;i++){
  // 	A.push_back(rand()%i);
  // }
  // for(int i=0;i<n;i++){
  // 	B.push_back(i);
  // }
  // random_shuffle(B.begin(),B.end());
  // if(main_(A,B)==0){
  // 	for(int i=0;i<A.size();i++)printf("%d ",A[i]);printf("\n");
  // 	for(int i=0;i<B.size();i++)printf("%d ",B[i]);printf("\n");

  // 	break;
  // }
  // }
}