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Submission #735249

# Submission time Handle Problem Language Result Execution time Memory
735249 2023-05-03T18:34:39 Z MasterTaster One-Way Streets (CEOI17_oneway) C++14
100 / 100
 761 ms 72664 KB 
#include <bits/stdc++.h>

#define ll long long
#define MAXN 100010
#define pii pair<int, int>
#define xx first
#define yy second
#define pb push_back

using namespace std;

int n, m, low[MAXN], tin[MAXN], tout[MAXN], timer, col[MAXN], logg;
vector<int> g[MAXN], gg[MAXN];
vector<pii> bridge, grane;
vector<pair<int, pii> >svi;
bool bio[MAXN];
map<pii, bool> b;
map<pii, int> dir, cnt;
int up[MAXN][25];

void dfs(int u, int p)
{
    bio[u]=true;
    tin[u]=low[u]=timer++;
    for (auto v:g[u])
    {
        if (v==p) continue;
        if (bio[v])
            low[u]=min(low[u], tin[v]);
        else
        {
            dfs(v, u);
            low[u]=min(low[u], low[v]);
            if (low[v]>tin[u] && cnt[{u, v}]==1) { /*cout<<u<<" bridge "<<v<<endl;*/ bridge.pb({u, v}); b[{u, v}]=b[{v, u}]=true; }
        }
    }
}

void dfs2(int u, int c)
{
    bio[u]=true;
    col[u]=c;
    for (auto v:g[u])
    {
        if (!bio[v] && !b[{u, v}]) dfs2(v, c);
    }
}

void dfs3(int u, int p)
{
    ///cout<<u<<" dfs3 "<<timer+1<<endl;
    bio[u]=true;
    tin[u]=++timer;
    up[u][0]=p;
    for (int i=1; i<=logg; i++) up[u][i]=up[up[u][i-1]][i-1];
    for (auto v:gg[u])
        if (!bio[v])
            dfs3(v, u);
    tout[u]=++timer;
}

bool isanc(int u, int v) ///is u ancestor of v?
{
    return (tin[u]<=tin[v] && tout[u]>=tout[v]);
}

int lca(int u, int v)
{
    ///cout<<tin[u]<<" "<<tout[u]<<" "<<tin[v]<<" "<<tout[v]<<endl;
    if (isanc(u, v)) return u;
    if (isanc(v, u)) return v;
    for (int i=logg; i>=0; i--)
    {
        if (!isanc(up[u][i], v)) u=up[u][i];
    }
    return up[u][0];
}

int main() {

    cin>>n>>m;
    for (int i=0; i<m; i++)
    {
        int u, v; cin>>u>>v;
        grane.pb({u, v}); cnt[{u, v}]++; cnt[{v, u}]++;
        g[u].pb(v);
        g[v].pb(u);
    }

    for (int i=1; i<=n; i++)
    {
        if (!bio[i])
            dfs(i, -1);
    }

    for (int i=1; i<=n; i++) bio[i]=false;
    int cc=1;
    for (int i=1; i<=n; i++)
    {
        if (!bio[i]) { dfs2(i, cc); cc++; }
    }

    //for (int i=1; i<=n; i++) cout<<col[i]<<" ";
    //cout<<endl;

    for (int i=0; i<bridge.size(); i++)
    {
        int u=col[bridge[i].xx], v=col[bridge[i].yy];
        ///cout<<"povezujem "<<u<<" "<<v<<endl;
        gg[u].pb(v); gg[v].pb(u);
    }
    for (int i=1; i<cc; i++) bio[i]=false;
    logg=ceil(log2(cc));
    timer=0;
    for (int i=1; i<cc; i++)
    {
        if (!bio[i]) dfs3(i, i);
    }

    int pp; cin>>pp;
    while (pp--)
    {
        int x, y;
        cin>>x>>y;
        x=col[x];
        y=col[y];
        if (x==y) continue;
        int xy=lca(x, y);
        svi.pb({tin[xy], {x, y}});
    }
    sort(svi.begin(), svi.end());
    for (auto par:svi)
    {
        int x=par.yy.xx; int y=par.yy.yy;
        if (x==y) continue;
        int xy=lca(x, y);
        //cout<<x<<" "<<y<<" "<<xy<<endl;
        while (x!=xy)
        {
            int p=up[x][0];
            if (dir[{x, p}]) break;
            //cout<<x<<" xp "<<p<<endl;
            dir[{x, p}]=1;
            dir[{p, x}]=2;
            x=p;
        }
        while (y!=xy)
        {
            int p=up[y][0];
            if (dir[{y, p}]) break;
            //cout<<y<<" yp "<<p<<endl;
            dir[{y, p}]=2;
            dir[{p, y}]=1;
            y=p;
        }
    }

    for (int i=0; i<m; i++)
    {
        int u, v; u=grane[i].xx; v=grane[i].yy;
        if (col[u]==col[v]) { cout<<'B'; continue; }
        u=col[u]; v=col[v];
        //cout<<u<<" uv "<<v<<endl;
        if (dir[{u, v}]==1) { cout<<'R'; }
        else if (dir[{u, v}]==2) { cout<<'L'; }
        else { cout<<'B'; }
    }
}
/*
3 5
1 2
2 1
3 4
4 3
2 3
4
1 3
1 2
3 4
1 1
 */

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:106:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |     for (int i=0; i<bridge.size(); i++)
      |                   ~^~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 4 ms 5272 KB Output is correct
4 Correct 5 ms 5460 KB Output is correct
5 Correct 5 ms 5588 KB Output is correct
6 Correct 4 ms 5204 KB Output is correct
7 Correct 5 ms 5588 KB Output is correct
8 Correct 5 ms 5532 KB Output is correct
9 Correct 4 ms 5204 KB Output is correct
10 Correct 4 ms 5204 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 4 ms 5272 KB Output is correct
4 Correct 5 ms 5460 KB Output is correct
5 Correct 5 ms 5588 KB Output is correct
6 Correct 4 ms 5204 KB Output is correct
7 Correct 5 ms 5588 KB Output is correct
8 Correct 5 ms 5532 KB Output is correct
9 Correct 4 ms 5204 KB Output is correct
10 Correct 4 ms 5204 KB Output is correct
11 Correct 214 ms 24484 KB Output is correct
12 Correct 276 ms 26496 KB Output is correct
13 Correct 257 ms 30112 KB Output is correct
14 Correct 385 ms 37640 KB Output is correct
15 Correct 366 ms 40532 KB Output is correct
16 Correct 531 ms 57020 KB Output is correct
17 Correct 530 ms 62148 KB Output is correct
18 Correct 476 ms 57108 KB Output is correct
19 Correct 535 ms 63952 KB Output is correct
20 Correct 245 ms 27272 KB Output is correct
21 Correct 194 ms 26532 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 4 ms 5272 KB Output is correct
4 Correct 5 ms 5460 KB Output is correct
5 Correct 5 ms 5588 KB Output is correct
6 Correct 4 ms 5204 KB Output is correct
7 Correct 5 ms 5588 KB Output is correct
8 Correct 5 ms 5532 KB Output is correct
9 Correct 4 ms 5204 KB Output is correct
10 Correct 4 ms 5204 KB Output is correct
11 Correct 214 ms 24484 KB Output is correct
12 Correct 276 ms 26496 KB Output is correct
13 Correct 257 ms 30112 KB Output is correct
14 Correct 385 ms 37640 KB Output is correct
15 Correct 366 ms 40532 KB Output is correct
16 Correct 531 ms 57020 KB Output is correct
17 Correct 530 ms 62148 KB Output is correct
18 Correct 476 ms 57108 KB Output is correct
19 Correct 535 ms 63952 KB Output is correct
20 Correct 245 ms 27272 KB Output is correct
21 Correct 194 ms 26532 KB Output is correct
22 Correct 757 ms 67840 KB Output is correct
23 Correct 749 ms 65288 KB Output is correct
24 Correct 725 ms 65284 KB Output is correct
25 Correct 699 ms 72664 KB Output is correct
26 Correct 761 ms 67172 KB Output is correct
27 Correct 714 ms 65308 KB Output is correct
28 Correct 116 ms 8764 KB Output is correct
29 Correct 295 ms 29932 KB Output is correct
30 Correct 301 ms 29984 KB Output is correct
31 Correct 265 ms 29720 KB Output is correct
32 Correct 416 ms 40384 KB Output is correct