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답안 #425896

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
425896 2021-06-13T12:15:33 Z oleh1421 One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 18008 KB 
#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
const int N=100010;
const ll mod=1000000007;
const ll inf=1e15;
int a[N],b[N];
int x[N],y[N];
vector<pair<int,int> >g[N];
int timer=0;
int tin[N],tout[N],fup[N];
bool used[N];
bool imp[N];
void dfs(int v,int pr){
    used[v]=true;
    tin[v]=fup[v]=++timer;
    for (auto cur:g[v]){
        int to=cur.first;
        int ind=cur.second;
        if (ind==pr) continue;
        if (!used[to]){
            dfs(to,ind);
            if (fup[to]>tin[v]) imp[ind]=true;
            fup[v]=min(fup[v],fup[to]);
        } else {
            fup[v]=min(fup[v],tin[to]);
        }
    }
}
int comp[N];
int num=0;
void dfs1(int v){
    comp[v]=num;
    for (auto cur:g[v]){
        int to=cur.first;
        int ind=cur.second;
        if (!imp[ind] && !comp[to]){
            dfs1(to);
        }
    }
}
vector<pair<int,int> >t[N];
const int L=20;
int up[N][L];

void dfs2(int v,int pr){
    up[v][0]=pr;
//    cout<<"0 "<<v<<" "<<pr<<endl;
    for (int i=1;i<L;i++){
        up[v][i]=up[up[v][i-1]][i-1];

    }
    used[v]=true;
    tin[v]=++timer;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (to==pr) continue;
        dfs2(to,v);
    }

    tout[v]=timer;
}
bool upper(int a,int b){
    return (tin[a]<=tin[b] && tout[b]<=tout[a]);
}
int lca(int a,int b){
    if (upper(a,b)) return a;
    if (upper(b,a)) return b;
    for (int i=L-1;i>=0;i--){
        if (!upper(up[a][i],b)) a=up[a][i];
    }
    return up[a][0];
}
int add[N][2];
char ans[N];
void dfs3(int v,int pr,int ind){
    used[v]=true;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (to==pr) continue;
        dfs3(to,v,ind);
        add[v][0]+=add[to][0];
        add[v][1]+=add[v][1];
    }
//    if (add[v][0] && add[v][1]) exit(1);
    if (add[v][0]){
        if (comp[a[ind]]==v) ans[ind]='R';
        else ans[ind]='L';
    } else if (add[v][1]){
        if (comp[a[ind]]==v) ans[ind]='L';
        else ans[ind]='R';
    } else {

    }

}
pair<int,int> p[N];
void dfs4(int v){
    used[v]=true;
    for (auto cur:t[v]){
        int to=cur.first;
        int ind=cur.second;
        if (used[to]) continue;
        p[to]={v,ind};
        dfs4(to);
    }

}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n,m;cin>>n>>m;
    for (int i=1;i<=m;i++){
        cin>>a[i]>>b[i];
        g[a[i]].push_back({b[i],i});
        g[b[i]].push_back({a[i],i});
        ans[i]='B';
    }
    int k;cin>>k;
    for (int i=1;i<=k;i++){
        cin>>x[i]>>y[i];
    }
    for (int i=1;i<=n;i++){
        if (!used[i]){
            dfs(i,0);
        }
    }

    for (int i=1;i<=n;i++){
        if (!comp[i]){
            num++;
            dfs1(i);
        }
    }
    for (int v=1;v<=n;v++){
        for (auto cur:g[v]){
            int to=cur.first;
            int ind=cur.second;
            if (imp[ind]){
                t[comp[v]].push_back({comp[to],ind});
            }
        }
    }
    for (int i=1;i<=k;i++){
        for (int j=1;j<=n;j++) used[j]=false;
        x[i]=comp[x[i]];
        y[i]=comp[y[i]];
        dfs4(x[i]);
        int cur=y[i];
        while (cur!=x[i]){
            int to=p[cur].first;
            int ind=p[cur].second;
            if (imp[ind]){
                if (comp[a[ind]]==to) ans[ind]='R';
                else ans[ind]='L';
            }
            cur=to;
        }
    }
//    for (int i=1;i<=n;i++) used[i]=false,tin[i]=0;
//    tin[0]=0;
//    timer=0;
//    for (int i=1;i<=num;i++){
//        if (!used[i]) dfs2(i,0);
//    }
//    tout[0]=timer;
//    for (int i=1;i<=k;i++){
//        x[i]=comp[x[i]];
//        y[i]=comp[y[i]];
//        int lc=lca(x[i],y[i]);
//        add[x[i]][0]++;
//        add[y[i]][1]++;
//        add[lc][0]--;
//        add[lc][1]--;
//    }
//    for (int i=1;i<=num;i++) used[i]=false;
//    for (int i=1;i<=num;i++) {
//        if (!used[i]){
//            dfs3(i,0,0);
//        }
//    }
    for (int i=1;i<=m;i++) cout<<ans[i];
    cout<<endl;
    return 0;
}

Compilation message

oneway.cpp: In function 'void dfs2(int, int)':
oneway.cpp:57:13: warning: unused variable 'ind' [-Wunused-variable]
   57 |         int ind=cur.second;
      |             ^~~

Subtask #1
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 7 ms 5196 KB Output is correct
6 Correct 5 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 5 ms 5068 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct

Subtask #2
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 7 ms 5196 KB Output is correct
6 Correct 5 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 5 ms 5068 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 49 ms 10168 KB Output is correct
12 Correct 65 ms 11136 KB Output is correct
13 Correct 64 ms 12412 KB Output is correct
14 Correct 121 ms 13656 KB Output is correct
15 Correct 157 ms 14240 KB Output is correct
16 Correct 122 ms 15532 KB Output is correct
17 Correct 1193 ms 17044 KB Output is correct
18 Correct 860 ms 15556 KB Output is correct
19 Correct 1108 ms 18008 KB Output is correct
20 Correct 51 ms 10648 KB Output is correct
21 Correct 54 ms 10548 KB Output is correct

Subtask #3
0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4940 KB Output is correct
2 Correct 3 ms 5068 KB Output is correct
3 Correct 4 ms 5068 KB Output is correct
4 Correct 4 ms 5068 KB Output is correct
5 Correct 7 ms 5196 KB Output is correct
6 Correct 5 ms 5068 KB Output is correct
7 Correct 5 ms 5196 KB Output is correct
8 Correct 5 ms 5068 KB Output is correct
9 Correct 4 ms 5068 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 49 ms 10168 KB Output is correct
12 Correct 65 ms 11136 KB Output is correct
13 Correct 64 ms 12412 KB Output is correct
14 Correct 121 ms 13656 KB Output is correct
15 Correct 157 ms 14240 KB Output is correct
16 Correct 122 ms 15532 KB Output is correct
17 Correct 1193 ms 17044 KB Output is correct
18 Correct 860 ms 15556 KB Output is correct
19 Correct 1108 ms 18008 KB Output is correct
20 Correct 51 ms 10648 KB Output is correct
21 Correct 54 ms 10548 KB Output is correct
22 Execution timed out 3066 ms 17780 KB Time limit exceeded
23 Halted 0 ms 0 KB -