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Submission #990418

# Submission time Handle Problem Language Result Execution time Memory
990418 2024-05-30T11:29:20 Z huutuan Islands (IOI08_islands) C++14
100 / 100
 453 ms 117588 KB 
#include<bits/stdc++.h>

using namespace std;

const int N=1e6+10;
int n, vis[N], _vis[N], par[N], wpar[N], on_cycle[N];
vector<pair<int, int>> g[N];
long long pf[N], f[N][2];
int cycle[N];
stack<int> stk;

void dfs(int _u){
   stk.push(_u);
   while (stk.size()){
      int u=stk.top();
      if (vis[u]){
         stk.pop();
         long long mx1=-1e18, mx2=-1e18;
         for (auto &e:g[u]){
            int v=e.first, w=e.second;
            if (on_cycle[v]) continue;
            long long val=f[v][0]+w;
            f[u][0]=max(f[u][0], val);
            f[u][1]=max(f[u][1], f[v][1]);
            if (mx1<val) mx2=mx1, mx1=val;
            else mx2=max(mx2, val);
         }
         f[u][1]=max({f[u][1], f[u][0], mx1+mx2});
         continue;
      }
      vis[u]=1;
      for (auto &e:g[u]){
         int v=e.first;
         if (on_cycle[v]) continue;
         stk.push(v);
      }
   }
}

int32_t main(){
   ios_base::sync_with_stdio(false);
   cin.tie(nullptr);
   cin >> n;
   for (int i=1; i<=n; ++i){
      int j, k; cin >> j >> k;
      g[j].emplace_back(i, k);
      par[i]=j;
      wpar[i]=k;
   }
   long long ans=0;
   for (int i=1; i<=n; ++i) if (!vis[i]){
      int L=0, R=0;
      long long cur=0;
      int u=i;
      while (1){
         if (_vis[u]) break;
         _vis[u]=1;
         cycle[R++]=u;
         u=par[u];
      }
      L=find(cycle+L, cycle+R, u)-cycle;
      for (int j=L; j<R; ++j) on_cycle[cycle[j]]=1;
      for (int j=L; j<R; ++j){
         dfs(cycle[j]);
         cur=max(cur, f[cycle[j]][1]);
      }
      pf[L]=0;
      for (int j=L; j<R; ++j){
         pf[j+1]=pf[j]+wpar[cycle[j]];
      }
      long long sum=pf[R];
      long long mx1=-1e18, mx2=-1e18;
      for (int j=L; j<R; ++j){
         cur=max(cur, f[cycle[j]][0]+pf[j]+mx1);
         cur=max(cur, f[cycle[j]][0]-pf[j]+mx2);
         mx1=max(mx1, f[cycle[j]][0]-pf[j]);
         mx2=max(mx2, f[cycle[j]][0]+sum+pf[j]);
      }
      ans+=cur;
   }
   cout << ans << '\n';
   return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 31068 KB Output is correct
2 Correct 5 ms 31244 KB Output is correct
3 Correct 5 ms 31064 KB Output is correct
4 Correct 4 ms 31068 KB Output is correct
5 Correct 5 ms 31068 KB Output is correct
6 Correct 4 ms 31184 KB Output is correct
7 Correct 4 ms 31068 KB Output is correct
8 Correct 4 ms 31068 KB Output is correct
9 Correct 4 ms 31068 KB Output is correct
10 Correct 4 ms 31068 KB Output is correct
11 Correct 5 ms 31068 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 31068 KB Output is correct
2 Correct 6 ms 31320 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 31324 KB Output is correct
2 Correct 5 ms 31324 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 31832 KB Output is correct
2 Correct 12 ms 32728 KB Output is correct
3 Correct 9 ms 32092 KB Output is correct
4 Correct 6 ms 31580 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 33368 KB Output is correct
2 Correct 20 ms 35684 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 40 ms 41940 KB Output is correct
2 Correct 46 ms 49492 KB Output is correct
3 Correct 48 ms 52052 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 75 ms 55636 KB Output is correct
2 Correct 91 ms 61788 KB Output is correct
3 Correct 94 ms 73812 KB Output is correct
4 Correct 108 ms 68692 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 157 ms 68788 KB Output is correct
2 Correct 301 ms 85904 KB Output is correct
3 Correct 137 ms 72764 KB Output is correct
4 Correct 172 ms 84304 KB Output is correct
5 Correct 161 ms 82004 KB Output is correct
6 Correct 453 ms 78956 KB Output is correct
7 Correct 168 ms 87120 KB Output is correct

Subtask #9
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 204 ms 96852 KB Output is correct
2 Correct 198 ms 103764 KB Output is correct
3 Correct 179 ms 117588 KB Output is correct
4 Correct 177 ms 107088 KB Output is correct
5 Correct 163 ms 95316 KB Output is correct
6 Correct 185 ms 96848 KB Output is correct
7 Correct 448 ms 94828 KB Output is correct