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Submission #466241

# Submission time Handle Problem Language Result Execution time Memory
466241 2021-08-18T11:38:37 Z ivan_tudor Star Trek (CEOI20_startrek) C++14
38 / 100
 721 ms 20132 KB 
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
const int MOD = 1e9 + 7;
int tp[N], tpr[N];
int crit[N], critr[N];
vector<int> gr[N];
void add(long long &x, long long y){
  y%=MOD;
  x+=y;
  if(x>=MOD)
    x-=MOD;
  if(x<0)
    x+=MOD;
}
void add(int &x, long long y){
  y%=MOD;
  x+=y;
  if(x>=MOD)
    x-=MOD;
  if(x<0)
    x+=MOD;
}
void dfs(int nod, int dad){
  tp[nod] = 0;
  int nr0 = 0, sum = 0, unq = 0;
  for(auto x:gr[nod]){
    if(x != dad){
      dfs(x, nod);
      if(tp[x] == 0)
        nr0++, unq = crit[x];
      sum += crit[x];
    }
  }
  if(nr0 == 0){
    tp[nod] = 0;
    crit[nod] = sum + 1;
  }
  else if(nr0 == 1){
    tp[nod] = 1;
    crit[nod] = unq;
  }
  else{
    tp[nod] = 1;
    crit[nod] = 0;
  }
}
void changeroot(int nod, int dad){
  int OLDTP = tp[nod], OLDCRIT = crit[nod];
  int nr0 = 0, sum = 0, unq = 0;
  for(auto x:gr[nod]){
    if(tp[x] == 0 )
      nr0++, unq = crit[x];
    sum += crit[x];
  }
  if(nr0 == 0)
    tp[nod] = 0;
  else
    tp[nod] = 1;
  if(tp[nod] == 0){
    crit[nod] = sum + 1;
  }
  else if(tp[nod] == 1){
    crit[nod] = 0;
    if(nr0 == 1)
      crit[nod] = unq;
  }
  critr[nod] = crit[nod];
  tpr[nod] = tp[nod];

  for(auto x:gr[nod]){
    if(x == dad)
      continue;
    int oldtp = tp[nod], oldcrit = crit[nod];
    if(tp[nod] == 0){
      tp[nod] = 0;
      crit[nod] = sum + 1 - crit[x];
    }
    else{
      if(tp[x] == 1){
        tp[nod] = 1;
        crit[nod] = oldcrit;
      }
      else{
        if(nr0 == 1){
          tp[nod] = 0;
          crit[nod] = sum + 1 - crit[x];
        }
        else if(nr0 == 2){
          tp[nod] = 1;
          int othunq = 0;
          for(auto vc:gr[nod]){
            if(vc == x)
              continue;
            if(tp[vc] == 0)
              othunq = crit[vc];
          }
          crit[nod] = othunq;
        }
        else if(nr0 >= 3){
          tp[nod] = 1;
          crit[nod] = 0;
        }
      }

    }

    changeroot(x, nod);

    tp[nod] = oldtp;
    crit[nod] = oldcrit;
  }

  tp[nod] = OLDTP;
  crit[nod] = OLDCRIT;
}
int main()
{
  //freopen(".in","r",stdin);
  ios::sync_with_stdio(false);
  cin.tie(0),cout.tie(0);
  int n, d;
  cin>>n>>d;
  for(int i = 1; i < n; i++){
    int u, v;
    cin>>u>>v;
    gr[u].push_back(v);
    gr[v].push_back(u);
  }
  dfs(1, 0);
  changeroot(1, 0);
  long long nr0 = 0, sumc0= 0, nr1 = 0, sumc1= 0;
  for(int i = 1; i<=n; i++){
    if(tpr[i] == 0){
      nr0++;
      add(sumc0, critr[i]);
    }
    else{
      nr1++;
      add(sumc1, critr[i]);
    }
    cerr<<tpr[i]<<" "<<critr[i]<<"\n";
  }
  cerr<<"\n";
  if(tpr[1] == 0){
    cout<<1LL * critr[1] * nr0 % MOD;
  }
  else{
    cout<<(1LL * n * n % MOD - 1LL * critr[1] * nr0 % MOD + MOD) % MOD;
  }
  return 0;
}

Subtask #1
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Incorrect 8 ms 2636 KB Output isn't correct

Subtask #2
0 / 7.0

# Verdict Execution time Memory Grader output
1 Incorrect 2 ms 2636 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #3
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 3 ms 2636 KB Output is correct
3 Correct 2 ms 2616 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 3 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct

Subtask #4
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 3 ms 2636 KB Output is correct
3 Correct 2 ms 2616 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 3 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 9 ms 2764 KB Output is correct
8 Correct 8 ms 2764 KB Output is correct
9 Correct 8 ms 2676 KB Output is correct
10 Correct 9 ms 2636 KB Output is correct
11 Correct 10 ms 2636 KB Output is correct

Subtask #5
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 3 ms 2636 KB Output is correct
3 Correct 2 ms 2616 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 3 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 9 ms 2764 KB Output is correct
8 Correct 8 ms 2764 KB Output is correct
9 Correct 8 ms 2676 KB Output is correct
10 Correct 9 ms 2636 KB Output is correct
11 Correct 10 ms 2636 KB Output is correct
12 Correct 716 ms 14216 KB Output is correct
13 Correct 721 ms 20132 KB Output is correct
14 Correct 700 ms 9084 KB Output is correct
15 Correct 677 ms 8996 KB Output is correct
16 Correct 679 ms 8952 KB Output is correct

Subtask #6
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 3 ms 2636 KB Output is correct
3 Correct 2 ms 2616 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 3 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 9 ms 2764 KB Output is correct
8 Correct 8 ms 2764 KB Output is correct
9 Correct 8 ms 2676 KB Output is correct
10 Correct 9 ms 2636 KB Output is correct
11 Correct 10 ms 2636 KB Output is correct
12 Correct 2 ms 2648 KB Output is correct
13 Incorrect 8 ms 2636 KB Output isn't correct
14 Halted 0 ms 0 KB -

Subtask #7
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Correct 3 ms 2636 KB Output is correct
3 Correct 2 ms 2616 KB Output is correct
4 Correct 2 ms 2636 KB Output is correct
5 Correct 3 ms 2636 KB Output is correct
6 Correct 2 ms 2636 KB Output is correct
7 Correct 9 ms 2764 KB Output is correct
8 Correct 8 ms 2764 KB Output is correct
9 Correct 8 ms 2676 KB Output is correct
10 Correct 9 ms 2636 KB Output is correct
11 Correct 10 ms 2636 KB Output is correct
12 Correct 716 ms 14216 KB Output is correct
13 Correct 721 ms 20132 KB Output is correct
14 Correct 700 ms 9084 KB Output is correct
15 Correct 677 ms 8996 KB Output is correct
16 Correct 679 ms 8952 KB Output is correct
17 Correct 2 ms 2648 KB Output is correct
18 Incorrect 8 ms 2636 KB Output isn't correct
19 Halted 0 ms 0 KB -

Subtask #8
0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2636 KB Output is correct
2 Incorrect 8 ms 2636 KB Output isn't correct