oj.uz

Submission #137073

# Submission time Handle Problem Language Result Execution time Memory
137073 2019-07-27T04:08:47 Z thebes One-Way Streets (CEOI17_oneway) C++14
100 / 100
 235 ms 31420 KB 
#include <bits/stdc++.h>
using namespace std;

const int MN = 1e5+5, LG = 19;
int N, M, Q, S, i, x, y, vis[MN][2], sp[MN][LG], cmp[MN], st[MN], nxt, ans[MN], u[MN], d[MN], dep[MN], cnt, vs[MN];
vector<pair<int,int>> adj[MN], cadj[MN];
stack<int> s;
pair<int,int> ree[MN];
string ans2;

void dfs(int n,int id){
    vis[n][0]=vis[n][1]=++nxt;
    st[n]=1; s.push(n);
    for(auto v : adj[n]){
        if(v.second==id) continue;
        if(!vis[v.first][0]){
            dfs(v.first, v.second);
            vis[n][1]=min(vis[n][1],vis[v.first][1]);
        }
        else if(st[v.first]){
            vis[n][1]=min(vis[n][1],vis[v.first][0]);
        }
    }
    if(vis[n][0]==vis[n][1]){
        S++;
        while(s.size()&&s.top()!=n){
            int x = s.top(); s.pop();
            cmp[x] = S; st[x] = 0;
        }
        int x = s.top(); s.pop();
        cmp[x] = S; st[x] = 0;
    }
}

void ddfs(int n,int p,int d){
    sp[n][0] = p; dep[n] = d; vs[n]=1;
    for(auto v : cadj[n]){
        if(v.first==p) continue;
        ddfs(v.first, n, d+1);
    }
}

int lca(int x,int y){
    if(dep[x]<dep[y]) swap(x,y);
    for(int i=LG-1;i>=0;i--){
        if((1<<i)<=dep[x]-dep[y])
            x = sp[x][i];
    }
    if(x==y) return x;
    for(int i=LG-1;i>=0;i--){
        if(sp[x][i]!=sp[y][i]){
            x = sp[x][i];
            y = sp[y][i];
        }
    }
    return sp[x][0];
}

pair<int,int> solve(int n,int p){
    int a=u[n], b=d[n]; vs[n]=1;
    for(auto v : cadj[n]){
        if(v.first==p) continue;
        auto t = solve(v.first, n);
        a += t.first, b += t.second;
    }
    if(a>0){
        for(int i=0;i<cadj[n].size();i++){
            if(cadj[n][i].first==p){
                ans[cadj[n][i].second]=1;
                break;
            }
        }
    }
    else if(b>0){
        for(int i=0;i<cadj[n].size();i++){
            if(cadj[n][i].first==p){
                ans[cadj[n][i].second]=2;
                break;
            }
        }
    }
    return make_pair(a,b);
}

int main(){
    for(scanf("%d%d",&N,&M),i=1;i<=M;i++){
        scanf("%d%d",&x,&y);
        adj[x].push_back({y,i});
        adj[y].push_back({x,i});
        ree[i]={x,y};
    }
    for(i=1;i<=N;i++){
        if(!vis[i][0]) dfs(i,0);
    }
    for(i=1;i<=N;i++){
        for(auto v : adj[i]){
            if(cmp[v.first]!=cmp[i])
                cadj[cmp[i]].push_back({cmp[v.first],v.second});
        }
    }
    for(i=1;i<=N;i++){
        if(!vs[i]) ddfs(i,0,1);
    }
    for(int j=1;j<LG;j++){
        for(i=1;i<=S;i++)
            sp[i][j]=sp[sp[i][j-1]][j-1];
    }
    for(scanf("%d",&Q),i=1;i<=Q;i++){
        scanf("%d%d",&x,&y);
        if(cmp[x]==cmp[y]) continue;
        x = cmp[x], y = cmp[y];
        int a = lca(x,y);
        u[x]++; u[a]--;
        d[y]++; d[a]--;
    }
    memset(vs,0,sizeof(vs));
    for(i=1;i<=N;i++){
        if(!vs[i]) solve(i, 0);
    }
    for(i=1;i<=M;i++){
        if(ans[i]){
            tie(x,y)=ree[i];
            if(dep[cmp[x]]<dep[cmp[y]]){
                if(ans[i]==2) ans2.push_back('R');
                else ans2.push_back('L');
            }
            else{
                if(ans[i]==2) ans2.push_back('L');
                else ans2.push_back('R');
            }
        }
        else ans2.push_back('B');
    }
    printf("%s\n",ans2.c_str());
    return 0;
}

Compilation message

oneway.cpp: In function 'std::pair<int, int> solve(int, int)':
oneway.cpp:67:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<cadj[n].size();i++){
                     ~^~~~~~~~~~~~~~~
oneway.cpp:75:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<cadj[n].size();i++){
                     ~^~~~~~~~~~~~~~~
oneway.cpp: In function 'int main()':
oneway.cpp:86:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(scanf("%d%d",&N,&M),i=1;i<=M;i++){
         ~~~~~~~~~~~~~~~~~~~^~~~
oneway.cpp:87:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x,&y);
         ~~~~~^~~~~~~~~~~~~~
oneway.cpp:108:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(scanf("%d",&Q),i=1;i<=Q;i++){
         ~~~~~~~~~~~~~~^~~~
oneway.cpp:109:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x,&y);
         ~~~~~^~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5368 KB Output is correct
2 Correct 6 ms 5368 KB Output is correct
3 Correct 7 ms 5624 KB Output is correct
4 Correct 7 ms 5672 KB Output is correct
5 Correct 7 ms 5624 KB Output is correct
6 Correct 7 ms 5588 KB Output is correct
7 Correct 7 ms 5752 KB Output is correct
8 Correct 7 ms 5692 KB Output is correct
9 Correct 7 ms 5496 KB Output is correct
10 Correct 7 ms 5520 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5368 KB Output is correct
2 Correct 6 ms 5368 KB Output is correct
3 Correct 7 ms 5624 KB Output is correct
4 Correct 7 ms 5672 KB Output is correct
5 Correct 7 ms 5624 KB Output is correct
6 Correct 7 ms 5588 KB Output is correct
7 Correct 7 ms 5752 KB Output is correct
8 Correct 7 ms 5692 KB Output is correct
9 Correct 7 ms 5496 KB Output is correct
10 Correct 7 ms 5520 KB Output is correct
11 Correct 61 ms 13236 KB Output is correct
12 Correct 79 ms 15172 KB Output is correct
13 Correct 81 ms 17988 KB Output is correct
14 Correct 111 ms 21852 KB Output is correct
15 Correct 108 ms 23028 KB Output is correct
16 Correct 138 ms 24620 KB Output is correct
17 Correct 147 ms 26540 KB Output is correct
18 Correct 146 ms 25208 KB Output is correct
19 Correct 145 ms 28208 KB Output is correct
20 Correct 77 ms 16528 KB Output is correct
21 Correct 68 ms 16544 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 5368 KB Output is correct
2 Correct 6 ms 5368 KB Output is correct
3 Correct 7 ms 5624 KB Output is correct
4 Correct 7 ms 5672 KB Output is correct
5 Correct 7 ms 5624 KB Output is correct
6 Correct 7 ms 5588 KB Output is correct
7 Correct 7 ms 5752 KB Output is correct
8 Correct 7 ms 5692 KB Output is correct
9 Correct 7 ms 5496 KB Output is correct
10 Correct 7 ms 5520 KB Output is correct
11 Correct 61 ms 13236 KB Output is correct
12 Correct 79 ms 15172 KB Output is correct
13 Correct 81 ms 17988 KB Output is correct
14 Correct 111 ms 21852 KB Output is correct
15 Correct 108 ms 23028 KB Output is correct
16 Correct 138 ms 24620 KB Output is correct
17 Correct 147 ms 26540 KB Output is correct
18 Correct 146 ms 25208 KB Output is correct
19 Correct 145 ms 28208 KB Output is correct
20 Correct 77 ms 16528 KB Output is correct
21 Correct 68 ms 16544 KB Output is correct
22 Correct 235 ms 27788 KB Output is correct
23 Correct 218 ms 26240 KB Output is correct
24 Correct 208 ms 26552 KB Output is correct
25 Correct 220 ms 31420 KB Output is correct
26 Correct 217 ms 27768 KB Output is correct
27 Correct 207 ms 26568 KB Output is correct
28 Correct 50 ms 9720 KB Output is correct
29 Correct 98 ms 17228 KB Output is correct
30 Correct 99 ms 17528 KB Output is correct
31 Correct 95 ms 17604 KB Output is correct
32 Correct 146 ms 22264 KB Output is correct