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Submission #206652

# Submission time Handle Problem Language Result Execution time Memory
206652 2020-03-04T11:28:27 Z DodgeBallMan One-Way Streets (CEOI17_oneway) C++14
100 / 100
 573 ms 31336 KB 
#include <bits/stdc++.h>
#define pii pair<int, int>
#define x first
#define y second 

using namespace std;

const int N = 1e5 + 10;
const int M = 1e5 + 10;

vector<pii> edge, g[N], g2[N], query, coord;
int n, m, q, pre[N], low[N], lca[18][N], dep[N], co[N], e[N], dir[N], c;
bool bridge[M];
char label[N];

void find_bridge( int u, int p ) {
    static int idx = 0;
    pre[u] = low[u] = ++idx;
    for( pii v : g[u] ) if( !pre[v.x] ) {
        find_bridge( v.x, u );
        low[u] = min( low[u], low[v.x] );
        if( low[v.x] > pre[u] ) bridge[v.y] = 1; 
    } else if( v.x != p ) low[u] = min( low[u], pre[v.x] );
}

void component( int u, int p ) {
    co[u] = c;
    for( pii v : g[u] ) if( v.x != p ) {
        if( !co[v.x] && !bridge[v.y] ) component( v.x, u );
    }
}

void init_lca( int u, int p, int ee ) {
    //printf("%d\n",u);
    lca[0][u] = p, dep[u] = dep[p] + 1, e[u] = ee;
    for( int i = 1 ; i <= 17 ; i++ ) lca[i][u] = lca[i-1][lca[i-1][u]];
    for( pii v : g2[u] ) if( v.x != p ) init_lca( v.x, u, v.y );
}

int find_lca( int a, int b ) {
    if( dep[a] < dep[b] ) swap( a, b );
    for( int i = 17 ; i >= 0 ; i-- ) if( dep[lca[i][a]] >= dep[b] ) a = lca[i][a];
    if( a == b ) return a;
    for( int i = 17 ; i >= 0 ; i-- ) if( lca[i][a] != lca[i][b] ) a = lca[i][a], b = lca[i][b];
    return lca[0][a];
}

void direct( int x, int z, int di ) {
    if( x == z ) return ;
    if( dir[x] == 0 ) {
        dir[x] = di;
        int y = lca[0][x], i = e[x];
        //printf("y : %d i : %d\n",y,i);
        int a = co[edge[i].x], b = co[edge[i].y];
        if( di == -1 ) {
            if( a == x && b == y ) label[i] = 'R'; 
            else label[i] = 'L'; 
        } else {
            if( a == y && b == x ) label[i] = 'R';
            else label[i] = 'L';
        }
        direct( y, z, di );
    } 
}

int main() 
{
	scanf("%d %d",&n,&m);
    edge.emplace_back( pii( 0, 0 ) );
    for( int i = 1, a, b ; i <= m ; i++ ) {
        scanf("%d %d",&a,&b);
        if( a == b ) continue;
        g[a].emplace_back( pii( b, i ) ), g[b].emplace_back( pii( a, i ) );
        edge.emplace_back( pii( a, b ) );
    }
    for( int i = 1 ; i <= n ; i++ ) if( !pre[i] ) find_bridge( i, 0 );
    for( int i = 1 ; i <= n ; i++ ) if( !co[i] ) ++c, component( i, 0 );
    //for( int i = 1 ; i <= n ; i++ ) printf("%d ",co[i]);
    //printf("\n");
    for( int i = 1 ; i <= m ; i++ ) if( bridge[i] ) {
        int f = co[edge[i].x], t = co[edge[i].y];
        if( f == t ) continue ;
        g2[f].emplace_back( pii( t, i ) ), g2[t].emplace_back( pii( f, i ) );
    }
    for( int i = 1 ; i <= n ; i++ ) if( !dep[i] ) init_lca( i, 0, 0 );
    for( int i = 1 ; i <= m ; i++ ) label[i] = 'B';
    scanf("%d",&q);
    query.emplace_back( pii( 0, 0 ) );
    for( int i = 1, a, b ; i <= q ; i++ ) {
        scanf("%d %d",&a,&b);
        a = co[a], b = co[b];
        int c = find_lca( a, b );
        //printf("%d %d %d\n",a,b,c);
        query.emplace_back( pii( a, b ) );
        coord.emplace_back( pii( dep[c], i ) );
    }
    sort( coord.begin(), coord.end() );
    for( pii i : coord ) {
        int y = i.y;
        int a = query[y].x, b = query[y].y;
        int c = find_lca( a, b );
        //printf("%d %d %d %d\n",a,b,c,dep[c]);
        direct( a, c, -1 ), direct( b, c, 1 );
    }
    for( int i = 1 ; i <= m ; i++ ) printf("%c",label[i]);
    return 0;
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:68:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:71:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d",&a,&b);
         ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:87:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&q);
     ~~~~~^~~~~~~~~
oneway.cpp:90:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d",&a,&b);
         ~~~~~^~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5112 KB Output is correct
2 Correct 7 ms 5112 KB Output is correct
3 Correct 9 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 9 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 8 ms 5368 KB Output is correct
8 Correct 8 ms 5244 KB Output is correct
9 Correct 8 ms 5240 KB Output is correct
10 Correct 8 ms 5240 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5112 KB Output is correct
2 Correct 7 ms 5112 KB Output is correct
3 Correct 9 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 9 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 8 ms 5368 KB Output is correct
8 Correct 8 ms 5244 KB Output is correct
9 Correct 8 ms 5240 KB Output is correct
10 Correct 8 ms 5240 KB Output is correct
11 Correct 63 ms 12780 KB Output is correct
12 Correct 74 ms 14696 KB Output is correct
13 Correct 80 ms 17360 KB Output is correct
14 Correct 101 ms 20968 KB Output is correct
15 Correct 104 ms 22252 KB Output is correct
16 Correct 146 ms 23916 KB Output is correct
17 Correct 130 ms 25452 KB Output is correct
18 Correct 143 ms 24044 KB Output is correct
19 Correct 123 ms 26600 KB Output is correct
20 Correct 69 ms 15848 KB Output is correct
21 Correct 69 ms 15596 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 5112 KB Output is correct
2 Correct 7 ms 5112 KB Output is correct
3 Correct 9 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 9 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 8 ms 5368 KB Output is correct
8 Correct 8 ms 5244 KB Output is correct
9 Correct 8 ms 5240 KB Output is correct
10 Correct 8 ms 5240 KB Output is correct
11 Correct 63 ms 12780 KB Output is correct
12 Correct 74 ms 14696 KB Output is correct
13 Correct 80 ms 17360 KB Output is correct
14 Correct 101 ms 20968 KB Output is correct
15 Correct 104 ms 22252 KB Output is correct
16 Correct 146 ms 23916 KB Output is correct
17 Correct 130 ms 25452 KB Output is correct
18 Correct 143 ms 24044 KB Output is correct
19 Correct 123 ms 26600 KB Output is correct
20 Correct 69 ms 15848 KB Output is correct
21 Correct 69 ms 15596 KB Output is correct
22 Correct 573 ms 28388 KB Output is correct
23 Correct 503 ms 26988 KB Output is correct
24 Correct 483 ms 27024 KB Output is correct
25 Correct 461 ms 31336 KB Output is correct
26 Correct 476 ms 28136 KB Output is correct
27 Correct 431 ms 26900 KB Output is correct
28 Correct 95 ms 11756 KB Output is correct
29 Correct 132 ms 18668 KB Output is correct
30 Correct 135 ms 18668 KB Output is correct
31 Correct 138 ms 19056 KB Output is correct
32 Correct 218 ms 23024 KB Output is correct