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Submission #566217

# Submission time Handle Problem Language Result Execution time Memory
566217 2022-05-22T06:51:57 Z shahriarkhan One-Way Streets (CEOI17_oneway) C++14
100 / 100
 192 ms 27840 KB 
#include<bits/stdc++.h>
using namespace std ;

//1 = L
//2 = B
//3 = R

const int MX = 1e5 + 5 , LG = 25 ;

int bridge[MX] , up[MX][LG] , vis[MX] , ans[MX] , low[MX] , tin[MX] , tout[MX] , timer = 0 , sub[MX][2] ;

vector<pair<int,int> > adj[MX] , edges ;

void dfs(int s , int p , int idx_par)
{
    if(vis[s]) return ;
    up[s][0] = p , vis[s] = 1 , tin[s] = ++timer , low[s] = tin[s] ;
    for(int i = 1 ; i < LG ; ++i)
    {
        up[s][i] = up[up[s][i-1]][i-1] ;
    }
    for(pair<int,int> t : adj[s])
    {
        if(t.second==idx_par) continue ;
        if(vis[t.first]) low[s] = min(low[s],tin[t.first]) ;
        else
        {
            dfs(t.first,s,t.second) ;
            low[s] = min(low[s],low[t.first]) ;
            if(low[t.first]>tin[s]) bridge[t.second] = 1 ;
        }
    }
    tout[s] = ++timer ;
}

int is_ancestor(int u , int v)
{
    return ((tin[u]<=tin[v]) && (tout[u]>=tout[v])) ;
}

int find_lca(int u , int v)
{
    if(is_ancestor(u,v)) return u ;
    if(is_ancestor(v,u)) return v ;
    for(int i = LG - 1 ; i >= 0 ; --i)
    {
        if(!is_ancestor(up[u][i],v))
        {
            u = up[u][i] ;
        }
    }
    return up[u][0] ;
}

void find_ans(int s , int p , int idx)
{
    if(vis[s]) return ;
    vis[s] = 1 ;
    for(pair<int,int> t : adj[s])
    {
        if(t.first==p) continue ;
        if(!vis[t.first])
        {
            find_ans(t.first,s,t.second) ;
            sub[s][0] += sub[t.first][0] ;
            sub[s][1] += sub[t.first][1] ;
        }
    }
    if(bridge[idx])
    {
        if(sub[s][0])
        {
            if(edges[idx].second==s) ans[idx] = 3 ;
            else ans[idx] = 1 ;
        }
        else if(sub[s][1])
        {
            if(edges[idx].second==s) ans[idx] = 1 ;
            else ans[idx] = 3 ;
        }
        else ans[idx] = 2 ;
    }
    else ans[idx] = 2 ;
}

int main()
{
    int n , m ;
    scanf("%d%d",&n,&m) ;
    edges.push_back({0,0}) ;
    for(int i = 1 ; i <= m ; ++i)
    {
        int a , b ;
        scanf("%d%d",&a,&b) ;
        adj[a].push_back({b,i}) ;
        adj[b].push_back({a,i}) ;
        edges.push_back({a,b}) ;
    }
    for(int i = 1 ; i <= n ; ++i)
    {
        dfs(i,i,0) ;
    }
    int q ;
    scanf("%d",&q) ;
    while(q--)
    {
        int u , v ;
        scanf("%d%d",&u,&v) ;
        int lca = find_lca(u,v) ;
        ++sub[v][0] , --sub[lca][0] ;
        ++sub[u][1] , --sub[lca][1] ;
    }
    for(int i = 1 ; i <= n ; ++i)
    {
        vis[i] = 0 ;
    }
    for(int i = 1 ; i <= n ; ++i)
    {
        find_ans(i,0,0) ;
    }
    for(int i = 1 ; i <= m ; ++i)
    {
        if(!ans[i]) printf("B") ;
        else if(ans[i]==1) printf("L") ;
        else if(ans[i]==2) printf("B") ;
        else printf("R") ;
    }
    printf("\n") ;
    return 0 ;
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:89:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |     scanf("%d%d",&n,&m) ;
      |     ~~~~~^~~~~~~~~~~~~~
oneway.cpp:94:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   94 |         scanf("%d%d",&a,&b) ;
      |         ~~~~~^~~~~~~~~~~~~~
oneway.cpp:104:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |     scanf("%d",&q) ;
      |     ~~~~~^~~~~~~~~
oneway.cpp:108:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  108 |         scanf("%d%d",&u,&v) ;
      |         ~~~~~^~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2772 KB Output is correct
4 Correct 2 ms 2772 KB Output is correct
5 Correct 2 ms 2772 KB Output is correct
6 Correct 2 ms 2772 KB Output is correct
7 Correct 2 ms 2900 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2772 KB Output is correct
4 Correct 2 ms 2772 KB Output is correct
5 Correct 2 ms 2772 KB Output is correct
6 Correct 2 ms 2772 KB Output is correct
7 Correct 2 ms 2900 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 49 ms 11328 KB Output is correct
12 Correct 58 ms 13976 KB Output is correct
13 Correct 80 ms 17436 KB Output is correct
14 Correct 115 ms 21440 KB Output is correct
15 Correct 131 ms 22568 KB Output is correct
16 Correct 87 ms 21332 KB Output is correct
17 Correct 99 ms 23100 KB Output is correct
18 Correct 98 ms 21304 KB Output is correct
19 Correct 126 ms 24552 KB Output is correct
20 Correct 68 ms 15384 KB Output is correct
21 Correct 71 ms 15460 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2772 KB Output is correct
4 Correct 2 ms 2772 KB Output is correct
5 Correct 2 ms 2772 KB Output is correct
6 Correct 2 ms 2772 KB Output is correct
7 Correct 2 ms 2900 KB Output is correct
8 Correct 2 ms 2772 KB Output is correct
9 Correct 2 ms 2772 KB Output is correct
10 Correct 2 ms 2772 KB Output is correct
11 Correct 49 ms 11328 KB Output is correct
12 Correct 58 ms 13976 KB Output is correct
13 Correct 80 ms 17436 KB Output is correct
14 Correct 115 ms 21440 KB Output is correct
15 Correct 131 ms 22568 KB Output is correct
16 Correct 87 ms 21332 KB Output is correct
17 Correct 99 ms 23100 KB Output is correct
18 Correct 98 ms 21304 KB Output is correct
19 Correct 126 ms 24552 KB Output is correct
20 Correct 68 ms 15384 KB Output is correct
21 Correct 71 ms 15460 KB Output is correct
22 Correct 192 ms 24280 KB Output is correct
23 Correct 172 ms 22376 KB Output is correct
24 Correct 153 ms 22412 KB Output is correct
25 Correct 173 ms 27840 KB Output is correct
26 Correct 172 ms 23836 KB Output is correct
27 Correct 147 ms 22452 KB Output is correct
28 Correct 48 ms 6676 KB Output is correct
29 Correct 123 ms 16144 KB Output is correct
30 Correct 110 ms 16440 KB Output is correct
31 Correct 120 ms 16576 KB Output is correct
32 Correct 128 ms 20684 KB Output is correct