Submission #1027215

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027215		coldbr3w	One-Way Streets (CEOI17_oneway)	C++17	60 / 100	3072 ms	44352 KiB

oneway

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pll pair<long long, long long>
#define pb push_back
#define F first
#define S second
#define all(x) (x).begin(), (x).end()

const ll N = 2e5 + 100;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const ll block = 480;
ll n,m,p,timer=0;
struct ccjv{ll v, prv, nxt;};
vector<pll>adj[N];
vector<ccjv>g[N];
ll cmp[N], low[N], num[N], b[N], pa[N];
pll edge[N];
ll cur = 0;
vector<pll>order;
map<pll,ll>dir;
void pre_dfs(ll u, ll par){
    low[u] = num[u] = ++timer;
    for(auto x : adj[u]){
        ll v = x.F, idx = x.S;
        if(idx == par) continue;
        if(num[v]) low[u] = min(low[u], num[v]);
        else{
            pre_dfs(v, idx);
            low[u] = min(low[u], low[v]);
            if(low[v] == num[v]) {
                //cout << "bridge" << ' ' << u << ' ' << v << '\n';
                b[idx] = 1;
            }
        }
    }
}
void dfs_cmp(ll u, ll par){
    cmp[u] = cur;
    for(auto x : adj[u]){
        ll v = x.F, idx = x.S;
        if(idx == par) continue;
        if(b[idx]){
            if(cmp[v]) g[cmp[u]].pb({cmp[v], u, v}), g[cmp[v]].pb({cmp[u], v, u});
        }
        else if(!cmp[v]) dfs_cmp(v, idx);
    }
}
void dfs(ll u, ll par, ll b){
    if(u == b){
        for(auto x : order){
            dir[{x.F, x.S}] = 1;
            dir[{x.S, x.F}] = -1;
        }
    }
    for(auto x : g[u]){
        ll v = x.v;
        if(v == par) continue;
        order.pb({x.prv, x.nxt});
        dfs(v, u, b);
        order.pop_back();
    }
}
void to_thic_cau(){  
    cin >> n >> m;
    for(int i = 1; i <= m;i++){
        ll u,v; cin >> u >> v;
        edge[i] = {u, v};
        adj[u].pb({v, i});
        adj[v].pb({u, i});
    }
    for(int i = 1; i <= n;i++) if(!num[i]) pre_dfs(i, 0);
    for(int i = 1; i <= n;i++){
        if(!cmp[i]){
            ++cur;
            dfs_cmp(i, 0);
        }
    }
    cin >> p;
    for(int i = 1; i <= p;i++){
        ll a,b; cin >> a >> b;
        dfs(cmp[a], 0, cmp[b]);
        order.clear();
    }
    for(int i = 1; i <= m;i++){
        if(!b[i]){
            cout << 'B';
        }
        else{
            if(!dir[{edge[i].F, edge[i].S}]) cout << 'B';
            else if(dir[{edge[i].F, edge[i].S}] == 1) cout << 'R';
            else cout << 'L';
        }
    }
    cout << '\n';
}

signed main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll tc = 1;
    //cin >> tc;
    while(tc--) to_thic_cau();
}

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