Submission #631685

#	Time	Username	Problem	Language	Result	Execution time	Memory
631685		NintsiChkhaidze	One-Way Streets (CEOI17_oneway)	C++14	30 / 100	825 ms	262144 KiB

oneway

#include <bits/stdc++.h>
#define s second
#define f first
#define pb push_back
using namespace std;
 
const int N = 100005;
int tin[N],low[N],a[N],b[N],ID[N];
bool bridge[N],vis[N];
map <int,bool> O[N],C[N];
vector <int> adj[N],vec[N];
vector <pair<int,int> > v[N];
int k,idx,cnt;
 
void dfs(int x,int par){
    vis[x] = 1;
    tin[x] = low[x] = cnt++;
    for (auto [to,id]: v[x]){
        if (to == par) continue;

        if (vis[to]){
            low[x] = min(low[x], tin[to]);
        }else{
            dfs(to,x);
            low[x] = min(low[x], low[to]);
            if (low[to] > tin[x])
                bridge[id] = 1;
        }
    }
}
    
 
void dfs1(int x){
    ID[x] = idx;
    vis[x] = 1;
    for (auto [to,id]: v[x]){
        if (!vis[to] && !bridge[id]) dfs1(to);
        else if (!vis[to] && bridge[id]) vec[idx].pb(to);
    }
}
 
 
void dfs2(int x,int par){
    vis[x] = 1;
    tin[x] = tin[par] + 1;
    for (int to: adj[x]){
        if (vis[to]) continue;
        dfs2(to,x);
 
        for (int j = 1; j <= k; j++){
            O[x][j] |= O[to][j];
            C[x][j] |= C[to][j];
        }

    }
}
int main (){
    ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
    int n,m;
    cin>>n>>m;
    for (int i = 1; i <= m; i++){
        cin>>a[i]>>b[i];
        v[a[i]].pb({b[i],i});
        v[b[i]].pb({a[i],i});
    }

    for (int i= 1; i <= n; i++)
        if (!vis[i]) dfs(i,i); 

    for (int i = 1; i <= n; i++) {
        sort(v[i].begin(),v[i].end());
        for (int j = 1; j < v[i].size(); j++)
            if (v[i][j].f == v[i][j - 1].f){
                bridge[v[i][j].s] = bridge[v[i][j - 1].s] = 0;
            }
    }
    
    for (int i= 1; i <= n; i++) 
        vis[i] = 0;
 
    idx = 0;
    for (int i = 1; i <= n; i++)
        if (!vis[i]) idx++,dfs1(i);
    
    for (int i = 1; i <= n; i++) 
        vis[i] = tin[i] = 0;
 
    for (int i = 1; i <= n; i++)
        for (int x: vec[i]){
            adj[i].pb(ID[x]);
            adj[ID[x]].pb(i);
        }
    
    cin>>k;
    for (int i = 1; i <= k; i++){
        int x,y;
        cin>>x>>y;
        O[ID[x]][i] = C[ID[y]][i] = 1;
    }

    for (int i = 1; i <= n; i++)
        if (!vis[i]) dfs2(i,i);

    for (int i = 1; i <= m; i++){
        if (!bridge[i]) cout<<'B';
        else{
            int x = ID[a[i]],y = ID[b[i]],o=0,c=0;
            if (tin[x] >= tin[y]){
                for (int j = 1; j <= k; j++)
                    if (O[x][j] && !C[x][j]) o++;
                    else if (!O[x][j] && C[x][j]) c++;
                
                if(o && !c) cout<<'R';
                else if (!o && c) cout<<'L';
                else cout<<'B';
            }else{
                for (int j = 1; j <= k; j++)
                    if (O[y][j] && !C[y][j]) o++;
                    else if (!O[y][j] && C[y][j]) c++;

                if(o && !c) cout<<'L';
                else if (!o && c) cout<<'R';
                else cout<<'B';
            }
            
        }
    }
 
}

Compilation message (stderr)

oneway.cpp: In function 'void dfs(int, int)':
oneway.cpp:18:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   18 |     for (auto [to,id]: v[x]){
      |               ^
oneway.cpp: In function 'void dfs1(int)':
oneway.cpp:36:15: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   36 |     for (auto [to,id]: v[x]){
      |               ^
oneway.cpp: In function 'int main()':
oneway.cpp:72:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |         for (int j = 1; j < v[i].size(); j++)
      |                         ~~^~~~~~~~~~~~~
oneway.cpp:86:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   86 |         vis[i] = tin[i] = 0;
      |                  ~~~~~~~^~~

• Subtask 1: 30 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40