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답안 #425934

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
425934 2021-06-13T12:27:48 Z oleh1421 One-Way Streets (CEOI17_oneway) C++17
60 / 100
 3000 ms 26224 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 nxt=cur.second;
        if (to==pr) continue;
        dfs3(to,v,nxt);
        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++){
        x[i]=comp[x[i]];
        y[i]=comp[y[i]];
    }
    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++){
        for (int j=1;j<=n;j++) used[j]=false;
        int lc=lca(x[i],y[i]);
        dfs4(lc);
        int cur=y[i];
        while (cur!=lc){
            int to=p[cur].first;
            int ind=p[cur].second;
            if (comp[a[ind]]==to) {
                ans[ind]='R';

            }
            else {

                ans[ind]='L';
            }
            cur=to;
        }
        cur=x[i];
        while (cur!=lc){
            int to=p[cur].first;
            int ind=p[cur].second;
            if (comp[a[ind]]==to) {
                ans[ind]='L';
            }
            else {

                ans[ind]='R';
            }
            cur=to;
        }
    }
//    for (int i=1;i<=k;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 5068 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 5196 KB Output is correct
5 Correct 6 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 7 ms 5196 KB Output is correct
9 Correct 4 ms 5120 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 5068 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 5196 KB Output is correct
5 Correct 6 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 7 ms 5196 KB Output is correct
9 Correct 4 ms 5120 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 52 ms 10136 KB Output is correct
12 Correct 61 ms 11148 KB Output is correct
13 Correct 74 ms 12740 KB Output is correct
14 Correct 158 ms 15912 KB Output is correct
15 Correct 171 ms 17420 KB Output is correct
16 Correct 176 ms 23820 KB Output is correct
17 Correct 1412 ms 25088 KB Output is correct
18 Correct 1184 ms 23744 KB Output is correct
19 Correct 1275 ms 26224 KB Output is correct
20 Correct 85 ms 10692 KB Output is correct
21 Correct 56 ms 10720 KB Output is correct

Subtask #3
0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 5068 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 5196 KB Output is correct
5 Correct 6 ms 5196 KB Output is correct
6 Correct 4 ms 5068 KB Output is correct
7 Correct 6 ms 5196 KB Output is correct
8 Correct 7 ms 5196 KB Output is correct
9 Correct 4 ms 5120 KB Output is correct
10 Correct 4 ms 5068 KB Output is correct
11 Correct 52 ms 10136 KB Output is correct
12 Correct 61 ms 11148 KB Output is correct
13 Correct 74 ms 12740 KB Output is correct
14 Correct 158 ms 15912 KB Output is correct
15 Correct 171 ms 17420 KB Output is correct
16 Correct 176 ms 23820 KB Output is correct
17 Correct 1412 ms 25088 KB Output is correct
18 Correct 1184 ms 23744 KB Output is correct
19 Correct 1275 ms 26224 KB Output is correct
20 Correct 85 ms 10692 KB Output is correct
21 Correct 56 ms 10720 KB Output is correct
22 Execution timed out 3094 ms 25840 KB Time limit exceeded
23 Halted 0 ms 0 KB -