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Submission #588733

# Submission time Handle Problem Language Result Execution time Memory
588733 2022-07-04T01:22:38 Z Bench0310 Islands (IOI08_islands) C++17
90 / 100
 748 ms 131072 KB 
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int N=1000001;
int u[N];
int vidx[N];
int ucost[N];
bool in_cycle[N];
ll dp[N];
ll down[N];
array<int,3> v[2*N];
int vsz=0;
array<int,3> bad_edges[N];
int badsz=0;
int cycle[N];
int cyclesz=0;

int find_set(int a)
{
    if(a==u[a]) return a;
    else return u[a]=find_set(u[a]);
}

int merge_sets(int a,int b)
{
    a=find_set(a);
    b=find_set(b);
    if(a==b) return 0;
    u[b]=a;
    return 1;
}

void chmax(ll &a,ll b){a=max(a,b);}

void dfs(int a)
{
    cycle[cyclesz++]=a;
    ll one=0,two=0;
    for(int i=vidx[a];i<vsz&&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);
}

void go(int a,int p)
{
    for(int i=vidx[a];i<vsz&&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]);
    }
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin >> n;
    for(int i=1;i<=n;i++) u[i]=i;
    for(int a=1;a<=n;a++)
    {
        int b,c;
        cin >> b >> c;
        if(merge_sets(a,b))
        {
            v[vsz++]={a,b,c};
            v[vsz++]={b,a,c};
        }
        else bad_edges[badsz++]={a,b,c};
    }
    sort(v,v+vsz);
    for(int i=vsz-1;i>=0;i--) vidx[v[i][0]]=i;
    ll res=0;
    memset(u,0,sizeof(u));
    for(int o=0;o<badsz;o++)
    {
        auto [x,y,bad_cost]=bad_edges[o];
        dfs(x);
        ll now=dp[x];
        for(int i=0;i<cyclesz;i++) down[cycle[i]]=dp[cycle[i]]=0;
        cyclesz=0;
        int t=y;
        while(t!=0)
        {
            cycle[cyclesz++]=t;
            in_cycle[t]=1;
            t=u[t];
        }
        for(int i=0;i<cyclesz;i++) go(cycle[i],0);
        ll path=0;
        for(int i=0;i<cyclesz;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=cyclesz-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;
        cyclesz=0;
    }
    cout << res << "\n";
    return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4180 KB Output is correct
2 Correct 2 ms 4260 KB Output is correct
3 Correct 2 ms 4308 KB Output is correct
4 Correct 2 ms 4180 KB Output is correct
5 Correct 2 ms 4180 KB Output is correct
6 Correct 2 ms 4180 KB Output is correct
7 Correct 2 ms 4180 KB Output is correct
8 Correct 2 ms 4180 KB Output is correct
9 Correct 2 ms 4180 KB Output is correct
10 Correct 2 ms 4180 KB Output is correct
11 Correct 2 ms 4180 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4308 KB Output is correct
2 Correct 2 ms 4308 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4308 KB Output is correct
2 Correct 3 ms 4564 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5204 KB Output is correct
2 Correct 17 ms 7504 KB Output is correct
3 Correct 13 ms 5364 KB Output is correct
4 Correct 7 ms 4820 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 23 ms 8660 KB Output is correct
2 Correct 35 ms 10716 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 73 ms 16468 KB Output is correct
2 Correct 74 ms 22636 KB Output is correct
3 Correct 92 ms 31264 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 122 ms 24860 KB Output is correct
2 Correct 155 ms 48904 KB Output is correct
3 Correct 185 ms 58488 KB Output is correct
4 Correct 222 ms 73736 KB Output is correct

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 387 ms 59368 KB Output is correct
2 Correct 545 ms 102476 KB Output is correct
3 Correct 235 ms 44044 KB Output is correct
4 Correct 314 ms 82192 KB Output is correct
5 Correct 308 ms 83092 KB Output is correct
6 Correct 748 ms 53080 KB Output is correct
7 Correct 333 ms 111440 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 299 ms 131072 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -