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Submission #588730

# Submission time Handle Problem Language Result Execution time Memory
588730 2022-07-04T01:01:21 Z Bench0310 Islands (IOI08_islands) C++17
90 / 100
 909 ms 131072 KB 
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    vector<array<int,3>> v;
    vector<array<int,3>> bad_edges;
    vector<int> u(n+1,0);
    for(int i=1;i<=n;i++) u[i]=i;
    function<int(int)> find_set=[&](int a)->int
    {
        if(a==u[a]) return a;
        else return u[a]=find_set(u[a]);
    };
    auto merge_sets=[&](int a,int b)->int
    {
        a=find_set(a);
        b=find_set(b);
        if(a==b) return 0;
        u[b]=a;
        return 1;
    };
    for(int a=1;a<=n;a++)
    {
        int b,c;
        cin >> b >> c;
        if(merge_sets(a,b))
        {
            v.push_back({a,b,c});
            v.push_back({b,a,c});
        }
        else bad_edges.push_back({a,b,c});
    }
    sort(v.begin(),v.end());
    vector<int> vidx(n+1,0);
    for(int i=(int)v.size()-1;i>=0;i--) vidx[v[i][0]]=i;
    ll res=0;
    auto chmax=[&](ll &a,ll b){a=max(a,b);};
    u.assign(n+1,0);
    vector<int> ucost(n+1,0);
    vector<bool> in_cycle(n+1,0);
    vector<ll> dp(n+1,0);
    vector<ll> down(n+1,0);
    for(auto [x,y,bad_cost]:bad_edges)
    {
        vector<int> cc;
        vector<int> cycle;
        function<void(int)> dfs=[&](int a)
        {
            cc.push_back(a);
            ll one=0,two=0;
            for(int i=vidx[a];i<(int)v.size()&&v[i][0]==a;i++)
            {
                auto [_,to,c]=v[i];
                if(to==u[a]) continue;
                u[to]=a;
                ucost[to]=c;
                dfs(to);
                ll len=c+down[to];
                if(len>one){two=one; one=len;}
                else if(len>two){two=len;}
                chmax(dp[a],dp[to]);
                chmax(down[a],len);
            }
            chmax(dp[a],one+two);
        };
        dfs(x);
        ll now=dp[x];
        int t=y;
        while(t!=0)
        {
            cycle.push_back(t);
            in_cycle[t]=1;
            t=u[t];
        }
        for(int a:cc) down[a]=dp[a]=0;
        function<void(int,int)> go=[&](int a,int p)
        {
            for(int i=vidx[a];i<(int)v.size()&&v[i][0]==a;i++)
            {
                auto [_,to,c]=v[i];
                if(to==p||in_cycle[to]) continue;
                go(to,a);
                chmax(down[a],c+down[to]);
            }
        };
        for(int a:cycle) go(a,0);
        int len=cycle.size();
        ll path=0;
        for(int i=0;i<len;i++)
        {
            if(i>0) dp[cycle[i]]=dp[cycle[i-1]];
            chmax(dp[cycle[i]],path+down[cycle[i]]);
            path+=ucost[cycle[i]];
        }
        path=0;
        ll opt=0;
        for(int i=len-1;i>=0;i--)
        {
            path+=ucost[cycle[i]];
            chmax(opt,path+down[cycle[i]]);
            if(i>0) chmax(now,dp[cycle[i-1]]+bad_cost+opt);
        }
        res+=now;
    }
    cout << res << "\n";
    return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 212 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 212 KB Output is correct
5 Correct 1 ms 212 KB Output is correct
6 Correct 1 ms 320 KB Output is correct
7 Correct 1 ms 212 KB Output is correct
8 Correct 1 ms 320 KB Output is correct
9 Correct 1 ms 212 KB Output is correct
10 Correct 1 ms 212 KB Output is correct
11 Correct 1 ms 212 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 2 ms 332 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 3 ms 724 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 1352 KB Output is correct
2 Correct 24 ms 4164 KB Output is correct
3 Correct 12 ms 1740 KB Output is correct
4 Correct 7 ms 976 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 28 ms 5452 KB Output is correct
2 Correct 37 ms 7516 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 101 ms 14368 KB Output is correct
2 Correct 95 ms 20556 KB Output is correct
3 Correct 121 ms 29968 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 150 ms 22540 KB Output is correct
2 Correct 215 ms 48764 KB Output is correct
3 Correct 241 ms 58800 KB Output is correct
4 Correct 272 ms 76164 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 496 ms 75196 KB Output is correct
2 Correct 713 ms 120608 KB Output is correct
3 Correct 302 ms 43056 KB Output is correct
4 Correct 386 ms 84884 KB Output is correct
5 Correct 390 ms 86568 KB Output is correct
6 Correct 909 ms 56504 KB Output is correct
7 Correct 446 ms 131072 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 441 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -