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Submission #900359

# Submission time Handle Problem Language Result Execution time Memory
900359 2024-01-08T07:52:01 Z abcvuitunggio Islands (IOI08_islands) C++17
70 / 100
 351 ms 131072 KB 
#include <bits/stdc++.h>
using namespace std;
const int mxn=1000001;
const long long INF=1e18;
vector <int> ke[mxn],ve[mxn],V[mxn],tmp;
vector <long long> s;
int n,p[mxn],l[mxn],vis[mxn],vis2[mxn],root[mxn],cycle[mxn],idx;
long long dp[mxn],dp2[mxn],d[mxn],mx,res;
void dfs(int u){
    for (int v:ke[u]){
        d[v]=d[u]+l[v];
        dfs(v);
        dp[u]=max(dp[u],dp[v]+l[v]);
    }
}
void dfs2(int u){
    pair <long long, int> mx={-1,0},mx2={-1,0};
    for (int v:ke[u]){
        auto tmp=make_pair(dp[v]+l[v],v);
        if (tmp>mx){
            mx2=mx;
            mx=tmp;
        }
        else
            mx2=max(mx2,tmp);
    }
    for (int v:ke[u]){
        dp2[v]=max(dp2[u],(mx.second==v?mx2.first:mx.first))+l[v];
        dfs2(v);
    }
}
int main(){
    ios_base::sync_with_stdio(NULL);cin.tie(nullptr);
    cin >> n;
    for (int i=1;i<=n;i++)
        cin >> p[i] >> l[i];
    for (int i=1;i<=n;i++)
        if (!vis[i]){
            int j=i;
            tmp.clear();
            while (true){
                tmp.push_back(i);
                vis2[i]=tmp.size();
                i=p[i];
                if (vis[i]){
                    for (int j:tmp){
                        root[j]=root[i];
                        cycle[j]=cycle[i];
                        ke[p[j]].push_back(j);
                        vis[j]=1;
                    }
                    break;
                }
                if (vis2[i]){
                    for (int j=vis2[i]-1;j<tmp.size();j++){
                        root[tmp[j]]=tmp[j];
                        cycle[tmp[j]]=idx;
                        ve[idx].push_back(tmp[j]);
                    }
                    for (int j=0;j<vis2[i]-1;j++){
                        root[tmp[j]]=i;
                        ke[tmp[j+1]].push_back(tmp[j]);
                    }
                    for (int j:tmp){
                        cycle[j]=cycle[i];
                        vis[j]=1;
                    }
                    idx++;
                    break;
                }
            }
            i=j;
        }
    for (int i=1;i<=n;i++)
        if (root[i]==i){
            dfs(i);
            dfs2(i);
        }
    for (int i=1;i<=n;i++)
        V[root[i]].push_back(i);
    for (int i=0;i<idx;i++){
        int sz=ve[i].size();
        long long a=-INF,b=-INF;
        for (int j=0;j<sz;j++)
            s.push_back((s.empty()?0:s.back())+l[ve[i][(j?j:sz)-1]]);
        mx=0;
        for (int j=sz-1;j>=0;j--){
            for (int u:V[ve[i][j]]){
                long long val=max(max(dp[u],dp2[u]),d[u]+max(a-s[j],b+s.back()+s[j]));
                mx=max(mx,val);
            }
            a=max(a,dp[ve[i][j]]+s[j]);
            b=max(b,dp[ve[i][j]]-s[j]);
        }
        s.clear();
        res+=mx;
    }
    cout << res;
}

Compilation message

islands.cpp: In function 'int main()':
islands.cpp:55:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   55 |                     for (int j=vis2[i]-1;j<tmp.size();j++){
      |                                          ~^~~~~~~~~~~

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 18 ms 80732 KB Output is correct
2 Correct 17 ms 80732 KB Output is correct
3 Correct 17 ms 80732 KB Output is correct
4 Correct 17 ms 80728 KB Output is correct
5 Correct 19 ms 81232 KB Output is correct
6 Correct 17 ms 80984 KB Output is correct
7 Correct 17 ms 80732 KB Output is correct
8 Correct 19 ms 80728 KB Output is correct
9 Correct 17 ms 80732 KB Output is correct
10 Correct 17 ms 80732 KB Output is correct
11 Correct 18 ms 80732 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 80732 KB Output is correct
2 Correct 17 ms 80728 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 80704 KB Output is correct
2 Correct 19 ms 81044 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 83804 KB Output is correct
2 Correct 28 ms 87132 KB Output is correct
3 Correct 23 ms 84040 KB Output is correct
4 Correct 21 ms 83448 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 30 ms 88156 KB Output is correct
2 Correct 39 ms 90936 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 61 ms 98104 KB Output is correct
2 Correct 60 ms 99160 KB Output is correct
3 Correct 78 ms 104664 KB Output is correct

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 98 ms 115576 KB Output is correct
2 Correct 127 ms 128728 KB Output is correct
3 Correct 123 ms 124240 KB Output is correct
4 Runtime error 159 ms 131072 KB Execution killed with signal 9
5 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 189 ms 131072 KB Output is correct
2 Runtime error 351 ms 131072 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 201 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -