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Submission #588727

# Submission time Handle Problem Language Result Execution time Memory
588727 2022-07-04T00:51:28 Z Bench0310 Islands (IOI08_islands) C++17
80 / 100
 468 ms 131076 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,2>> v[n+1];
    vector<array<int,3>> bad_edges;
    vector<int> dsu_p(n+1,0);
    for(int i=1;i<=n;i++) dsu_p[i]=i;
    vector<int> dsu_sz(n+1,1);
    function<int(int)> find_set=[&](int a)->int
    {
        if(a==dsu_p[a]) return a;
        else return dsu_p[a]=find_set(dsu_p[a]);
    };
    auto merge_sets=[&](int a,int b)->int
    {
        a=find_set(a);
        b=find_set(b);
        if(a==b) return 0;
        if(dsu_sz[a]<dsu_sz[b]) swap(a,b);
        dsu_p[b]=a;
        dsu_sz[a]+=dsu_sz[b];
        return 1;
    };
    for(int a=1;a<=n;a++)
    {
        int b,c;
        cin >> b >> c;
        if(merge_sets(a,b))
        {
            v[a].push_back({b,c});
            v[b].push_back({a,c});
        }
        else bad_edges.push_back({a,b,c});
    }
    ll res=0;
    auto chmax=[&](ll &a,ll b){a=max(a,b);};
    vector<int> u(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);
    vector<ll> lbest(n+1,0);
    vector<ll> rbest(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(auto [to,c]:v[a])
            {
                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]=0;
        function<void(int,int)> go=[&](int a,int p)
        {
            for(auto [to,c]:v[a])
            {
                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) lbest[cycle[i]]=lbest[cycle[i-1]];
            chmax(lbest[cycle[i]],path+down[cycle[i]]);
            path+=ucost[cycle[i]];
        }
        path=0;
        for(int i=len-1;i>=0;i--)
        {
            path+=ucost[cycle[i]];
            if(i+1<len) rbest[cycle[i]]=rbest[cycle[i+1]];
            chmax(rbest[cycle[i]],path+down[cycle[i]]);
            if(i>0) chmax(now,lbest[cycle[i-1]]+bad_cost+rbest[cycle[i]]);
        }
        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 0 ms 212 KB Output is correct
5 Correct 1 ms 348 KB Output is correct
6 Correct 0 ms 212 KB Output is correct
7 Correct 0 ms 212 KB Output is correct
8 Correct 1 ms 212 KB Output is correct
9 Correct 0 ms 212 KB Output is correct
10 Correct 0 ms 340 KB Output is correct
11 Correct 1 ms 340 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 468 KB Output is correct
2 Correct 1 ms 468 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 444 KB Output is correct
2 Correct 2 ms 980 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 2260 KB Output is correct
2 Correct 18 ms 6404 KB Output is correct
3 Correct 11 ms 3028 KB Output is correct
4 Correct 6 ms 1620 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 31 ms 8672 KB Output is correct
2 Correct 38 ms 14120 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 85 ms 27040 KB Output is correct
2 Correct 87 ms 34416 KB Output is correct
3 Correct 120 ms 47600 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 140 ms 49816 KB Output is correct
2 Correct 214 ms 82772 KB Output is correct
3 Correct 200 ms 94764 KB Output is correct
4 Correct 263 ms 121112 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 334 ms 131072 KB Output is correct
2 Runtime error 468 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 333 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -