제출 #948631

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
948631		GrindMachine	One-Way Streets (CEOI17_oneway)	C++17	60 / 100	3042 ms	31220 KiB

oneway

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<array<int,3>> adj1[N];
vector<bool> vis(N);
vector<bool> bridge(N);
vector<int> tin(N), low(N);
int timer = 1;

void dfs1(int u, int pid){
    vis[u] = 1;
    tin[u] = low[u] = timer++;

    for(auto [v,id,dir] : adj1[u]){
        if(id == pid) conts;
        if(vis[v]){
            amin(low[u],tin[v]);
        }
        else{
            dfs1(v,id);
            amin(low[u],low[v]);
            if(low[v] > tin[u]){
                bridge[id] = 1;
            }
        }
    }
}

vector<int> col(N);

void dfs2(int u, int c){
    vis[u] = 1;
    col[u] = c;

    for(auto [v,id,dir] : adj1[u]){
        if(vis[v]) conts;
        if(bridge[id]) conts;
        dfs2(v,c);
    }
}

vector<pii> adj2[N];

struct lca_algo {
    // LCA template (for graphs with 1-based indexing)
 
    int LOG = 1;
    vector<int> depth;
    vector<vector<int>> up;
    vector<int> tin, tout;
    vector<int> pid;
    vector<bool> lca_vis;
    int timer = 1;
 
    lca_algo() {
 
    }
 
    lca_algo(int n) {
        lca_init(n);
    }
 
    void lca_init(int n) {
        while ((1 << LOG) < n) LOG++;
        up = vector<vector<int>>(n + 1, vector<int>(LOG, 1));
        depth = vector<int>(n + 1);
        tin = vector<int>(n + 1);
        tout = vector<int>(n + 1);
        pid = vector<int>(n + 1);
        lca_vis = vector<bool>(n + 1);

        rep1(i,n){
            if(!lca_vis[i]){
                lca_dfs(i,-1);
            }
        }
    }
 
    void lca_dfs(int node, int par) {
        lca_vis[node] = 1;
        tin[node] = timer++;
 
        for(auto [child, id] : adj2[node]) {
            if (child == par) conts;
 
            up[child][0] = node;
            rep1(j, LOG - 1) {
                up[child][j] = up[up[child][j - 1]][j - 1];
            }
 
            depth[child] = depth[node] + 1;
            pid[child] = id;

            lca_dfs(child, node);
        }
 
        tout[node] = timer-1;
    }
 
    int lift(int u, int k) {
        rep(j, LOG) {
            if (k & (1 << j)) {
                u = up[u][j];
            }
        }
 
        return u;
    }
 
    int query(int u, int v) {
        if (depth[u] < depth[v]) swap(u, v);
        int k = depth[u] - depth[v];
        u = lift(u, k);
 
        if (u == v) return u;
 
        rev(j, LOG - 1, 0) {
            if (up[u][j] != up[v][j]) {
                u = up[u][j];
                v = up[v][j];
            }
        }
 
        u = up[u][0];
        return u;
    }
 
    int get_dis(int u, int v) {
        int lca = query(u, v);
        return depth[u] + depth[v] - 2 * depth[lca];
    }
 
    bool is_ances(int u, int v){
        return tin[u] <= tin[v] and tout[u] >= tout[v];
    }
};

void solve(int test_case)
{
    int n,m; cin >> n >> m;
    vector<pii> edges(m+5);
    rep1(i,m){
        int u,v; cin >> u >> v;
        edges[i] = {u,v};
        adj1[u].pb({v,i,0}), adj1[v].pb({u,i,1});
    }
    int k; cin >> k;
    vector<pii> a(k+5);
    rep1(i,k) cin >> a[i].ff >> a[i].ss;

    rep1(u,n){
        if(vis[u]) conts;
        dfs1(u,-1);
    }

    rep1(u,n){
        assert(vis[u]);
    }

    fill(all(vis),0);
    int ptr = 0;
    rep1(u,n){
        if(vis[u]) conts;
        dfs2(u,++ptr);
    }

    rep1(u,n){
        for(auto [v,id,dir] : adj1[u]){
            if(dir) conts;
            if(col[u] != col[v]){
                int cu = col[u], cv = col[v];
                adj2[cu].pb({cv,id}), adj2[cv].pb({cu,id});
                edges[id] = {cu,cv};
            }
        }
    }

    lca_algo LCA(ptr);
    vector<char> ans(m+5);
    rep1(i,m) ans[i] = 'B';

    rep1(i,k){
        auto [u,v] = a[i];
        u = col[u], v = col[v];
        int lca = LCA.query(u,v);

        while(u != lca){
            int p = LCA.up[u][0];
            int id = LCA.pid[u];
            if(u == edges[id].ff){
                ans[id] = 'R';
            }
            else{
                ans[id] = 'L';
            }

            u = p;
        }

        while(v != lca){
            int p = LCA.up[v][0];
            int id = LCA.pid[v];
            if(v == edges[id].ff){
                ans[id] = 'L';
            }
            else{
                ans[id] = 'R';
            }

            v = p;
        }
    }

    rep1(i,m) cout << ans[i];
    cout << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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