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Submission #206658

# Submission time Handle Problem Language Result Execution time Memory
206658 2020-03-04T11:41:02 Z DodgeBallMan One-Way Streets (CEOI17_oneway) C++14
100 / 100
 580 ms 29296 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, int ee ) {
    static int idx = 0;
    pre[u] = low[u] = ++idx;
    for( pii v : g[u] ) if( !pre[v.x] ) {
        find_bridge( v.x, u, v.y );
        low[u] = min( low[u], low[v.x] );
        if( low[v.x] > pre[u] ) bridge[v.y] = 1; 
    } else if( v.y != ee ) 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 ) {
    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];
        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, 0 );
    for( int i = 1 ; i <= n ; i++ ) if( !co[i] ) ++c, component( i, 0 );
    for( int i = 1 ; i <= m ; i++ ) if( bridge[i] ) {
        int f = co[edge[i].x], t = co[edge[i].y];
        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 );
        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 );
        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:66:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:69:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d",&a,&b);
         ~~~~~^~~~~~~~~~~~~~~
oneway.cpp:82:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&q);
     ~~~~~^~~~~~~~~
oneway.cpp:85:14: 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 8 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 8 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 9 ms 5240 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 8 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 8 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 9 ms 5240 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 60 ms 11624 KB Output is correct
12 Correct 71 ms 13544 KB Output is correct
13 Correct 80 ms 16232 KB Output is correct
14 Correct 100 ms 19820 KB Output is correct
15 Correct 110 ms 21096 KB Output is correct
16 Correct 141 ms 22684 KB Output is correct
17 Correct 130 ms 24324 KB Output is correct
18 Correct 146 ms 22996 KB Output is correct
19 Correct 124 ms 25540 KB Output is correct
20 Correct 72 ms 14696 KB Output is correct
21 Correct 70 ms 14444 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 8 ms 5240 KB Output is correct
4 Correct 8 ms 5240 KB Output is correct
5 Correct 8 ms 5368 KB Output is correct
6 Correct 8 ms 5240 KB Output is correct
7 Correct 9 ms 5240 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 60 ms 11624 KB Output is correct
12 Correct 71 ms 13544 KB Output is correct
13 Correct 80 ms 16232 KB Output is correct
14 Correct 100 ms 19820 KB Output is correct
15 Correct 110 ms 21096 KB Output is correct
16 Correct 141 ms 22684 KB Output is correct
17 Correct 130 ms 24324 KB Output is correct
18 Correct 146 ms 22996 KB Output is correct
19 Correct 124 ms 25540 KB Output is correct
20 Correct 72 ms 14696 KB Output is correct
21 Correct 70 ms 14444 KB Output is correct
22 Correct 580 ms 26412 KB Output is correct
23 Correct 507 ms 24680 KB Output is correct
24 Correct 555 ms 24940 KB Output is correct
25 Correct 447 ms 29296 KB Output is correct
26 Correct 458 ms 25836 KB Output is correct
27 Correct 461 ms 24812 KB Output is correct
28 Correct 92 ms 10476 KB Output is correct
29 Correct 140 ms 16616 KB Output is correct
30 Correct 136 ms 16748 KB Output is correct
31 Correct 135 ms 17000 KB Output is correct
32 Correct 217 ms 20972 KB Output is correct