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Submission #53761

# Submission time Handle Problem Language Result Execution time Memory
53761 2018-07-01T06:57:36 Z 노영훈(#1436) Islands (IOI08_islands) C++11
57 / 100
 2000 ms 187008 KB 
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, ll> pil;
const int MX=1000010;
const ll inf=2e17;

int n, A[MX], C[MX];
vector<pil> G[MX];
bool done[MX];

ll D[MX];

bool vis[MX];

// list all vertices
void dfs1(int v, vector<int> &V){
    done[v]=true;
    V.push_back(v);
    for(pil &e:G[v]){
        int x=e.first;
        if(done[x]) continue;
        dfs1(x,V);
    }
}

// find cycle 
int found=-1;
int dep[MX], now;
void dfs2(int v, int p, vector<int> &V){
    dep[v]=++now;
    for(pil &e:G[v]){
        int x; ll c; tie(x,c)=e;
        if(p==x) continue;
        if(dep[x]>=0)
            found=x;
        else
            dfs2(x,v,V);
        if(found>=0){
            if(dep[v]>=dep[found]) V.push_back(v);
            return;
        }
    }
    --now;
}

// farthest point
ll dist[MX]; 
int dfs3(int v){
    int res=v;
    for(pil &e:G[v]){
        int x; ll c; tie(x,c)=e;
        if(dist[x]>=0) continue;
        dist[x]=dist[v]+c;
        int y=dfs3(x);
        if(dist[y]>dist[res]) res=y;
    }
    return res;
}
ll solve_tree(vector<int> &V){
    int s=V[0];

    for(int v:V) dist[v]=-1;
    dist[s]=0;
    int u=dfs3(s);

    for(int v:V) dist[v]=-1;
    dist[u]=0;
    int v=dfs3(u);

    return dist[v];
}

bool incyc[MX];
ll arm[MX];
// longest path from v in cyc
void dfs4(int v){
    arm[v]=0;
    for(pil &e:G[v]){
        int x; ll c; tie(x,c)=e;
        if(incyc[x] || arm[x]>=0) continue;
        dfs4(x);
        arm[v]=max(arm[v], arm[x]+c);
    }
}

ll Val[MX], Len[MX], Sum[MX];
ll Lft[MX], Rig[MX];

vector<int> V, cyc;
ll solve(int s){
    // cout<<"\nSOLVE ON "<<s<<'\n';
    V.clear(), cyc.clear();
    dfs1(s, V);

    found=-1, now=0;
    for(int v:V) dep[v]=-1;
    dfs2(s, -1, cyc);

    if(cyc.empty())
        return solve_tree(V);

    for(int v:V) arm[v]=-1;
    for(int v:cyc) incyc[v]=true, arm[v]=0;
    for(int v:cyc) dfs4(v);

    int sz=cyc.size();
    Sum[0]=0;
    for(int i=0; i<sz; i++){
        int v=cyc[i];
        Val[i]=arm[v];
        int nxt=cyc[(i+1)%sz];
        for(pil &e:G[v])
            if(e.first==nxt) Len[i]=e.second;
        Sum[i+1]=Sum[i]+Len[i];
    }
    ll res=0;
    for(int i=0; i<sz; i++)
        for(int j=i+1; j<sz; j++){
            ll dist=max(Sum[j]-Sum[i], Sum[sz]+Sum[i]-Sum[j]);
            ll now=dist+Val[i]+Val[j];

            // printf("%d - %d : %lld (%lld)\n", cyc[i], cyc[j], now, dist);
            res=max(res, now);
        }
    return res;
}

int main(){
    ios::sync_with_stdio(0); cin.tie(0);
    cin>>n;
    for(int u=1; u<=n; u++){
        int v, c; cin>>v>>c;
        A[u]=v, C[u]=c;
        if(v<u && A[v]==u){
            C[u]=max(C[u], C[v]);
            C[v]=-1;
        }
    }
    for(int i=1; i<=n; i++){
        if(C[i]<0) continue;
        G[i].push_back({A[i], C[i]});
        G[A[i]].push_back({i, C[i]});
    }
    ll ans=0;
    for(int i=1; i<=n; i++){
        if(done[i]) continue;
        ans+=solve(i);
    }
    cout<<ans;
    return 0;
}

Subtask #1
30.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 23928 KB Output is correct
2 Incorrect 26 ms 23928 KB Output isn't correct
3 Correct 23 ms 23988 KB Output is correct
4 Correct 23 ms 23988 KB Output is correct
5 Correct 27 ms 23988 KB Output is correct
6 Correct 22 ms 24020 KB Output is correct
7 Correct 25 ms 24124 KB Output is correct
8 Correct 26 ms 24124 KB Output is correct
9 Correct 22 ms 24124 KB Output is correct
10 Correct 27 ms 24124 KB Output is correct
11 Correct 27 ms 24124 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 28 ms 24224 KB Output is correct
2 Correct 21 ms 24224 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 24 ms 24224 KB Output is correct
2 Correct 30 ms 24480 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 39 ms 25408 KB Output is correct
2 Correct 229 ms 28440 KB Output is correct
3 Correct 46 ms 28440 KB Output is correct
4 Correct 32 ms 28440 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 361 ms 29868 KB Output is correct
2 Correct 506 ms 33136 KB Output is correct

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 467 ms 41376 KB Output is correct
2 Execution timed out 2065 ms 45356 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 1334 ms 54580 KB Output is correct
2 Execution timed out 2074 ms 81968 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 494 ms 99560 KB Output is correct
2 Execution timed out 2065 ms 152724 KB Time limit exceeded
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 595 ms 157048 KB Output is correct
2 Correct 721 ms 157048 KB Output is correct
3 Execution timed out 2077 ms 187008 KB Time limit exceeded
4 Halted 0 ms 0 KB -