답안 #53741 :: oj.uz

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
53741	2018-07-01T06:17:49 Z	노영훈(#1436)	Islands (IOI08_islands)	C++11	27 / 100	2000 ms	171080 KB

islands

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> 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(arm[x]<0) dfs4(x);
        if(!incyc[x])
            arm[v]=max(arm[v], arm[x]+c);
    }
}

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

ll solve(int s){
    // cout<<"\nSOLVE ON "<<s<<'\n';
    vector<int> V; // list of all vertices
    dfs1(s, V);

    vector<int> cyc;
    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[1]=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];
            res=max(res, now);
        }
    // [0, sz) 에서 .
    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(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
27.0 / 33.0

#	결과	실행 시간	메모리	Grader output
1	Correct	22 ms	23800 KB	Output is correct
2	Incorrect	21 ms	23912 KB	Output isn't correct
3	Correct	24 ms	24124 KB	Output is correct
4	Correct	22 ms	24124 KB	Output is correct
5	Correct	22 ms	24124 KB	Output is correct
6	Correct	21 ms	24124 KB	Output is correct
7	Correct	23 ms	24124 KB	Output is correct
8	Incorrect	22 ms	24240 KB	Output isn't correct
9	Correct	21 ms	24240 KB	Output is correct
10	Correct	21 ms	24240 KB	Output is correct
11	Correct	21 ms	24240 KB	Output is correct

Subtask #2
0 / 3.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	22 ms	24240 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #3
0 / 4.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	26 ms	24256 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #4
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	52 ms	25240 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #5
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	350 ms	29116 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #6
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	484 ms	38428 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #7
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Incorrect	1312 ms	48524 KB	Output isn't correct
2	Halted	0 ms	0 KB	-

Subtask #8
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Correct	385 ms	91936 KB	Output is correct
2	Execution timed out	2048 ms	133772 KB	Time limit exceeded
3	Halted	0 ms	0 KB	-

Subtask #9
0 / 10.0

#	결과	실행 시간	메모리	Grader output
1	Correct	623 ms	141256 KB	Output is correct
2	Correct	562 ms	141256 KB	Output is correct
3	Execution timed out	2061 ms	171080 KB	Time limit exceeded
4	Halted	0 ms	0 KB	-

답안 #53741

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