Submission #696206

#	Time	Username	Problem	Language	Result	Execution time	Memory
696206		hamidh100	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	182 ms	28696 KiB

oneway

/* In the name of God */

#include <iostream>
#include <iomanip>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string>
#include <string.h>
#include <algorithm>
#include <bitset>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <list>
#include <map>
#include <numeric>
#include <limits>
#include <limits.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef map<int, int> MPII;
typedef vector<int> VI;
typedef vector<ll> VL;
#define PB push_back
#define POP pop_back
#define MP make_pair
#define all(a) (a).begin(), (a).end()
#define SORT(a) sort(all(a))
#define REVERSE(a) reverse(all(a))
#define sep ' '
#define endl '\n'
#define dbg(x) cerr << '[' << #x << ": " << x << "]\n"
#define dbg2(x, y) cerr << '[' << #x << ": " << x << ", " << #y << ": " << y << "]\n"
#define Yes cout << "Yes\n"
#define YES cout << "YES\n"
#define No cout << "No\n"
#define NO cout << "NO\n"
#define OK cout << "OK\n"

const ll INF = (ll)2e18 + 1386;
const ld eps = 0.000000000000001;
const int MOD = 1e9 + 7;

inline int mod_add(int a, int b){ int res = a + b; return (res >= MOD? res - MOD : res); }
inline int mod_neg(int a, int b){ int res = (abs(a - b) < MOD? a - b : (a - b) % MOD); return (res < 0? res + MOD : res); }
inline int mod_mlt(int a, int b){ return (1ll * a * b % MOD); }
inline string intToString(ll a){ char x[100]; sprintf(x, "%lld", a); string s = x; return s; }
inline ll stringToInt(string s){ ll res; char x[100]; strcpy(x, s.c_str()); sscanf(x, "%lld", &res); return res; }
inline void fileIO(string i, string o){ freopen(i.c_str(), "r", stdin); freopen(o.c_str(), "w", stdout); }

const int MAXN = 2e5 + 5, LOG = 23;

int n, m, q, par[MAXN][LOG], h[MAXN], psU[MAXN], psD[MAXN], st[MAXN], mnback[MAXN], timer, ans[MAXN], jahat[MAXN];
bool boreshi[MAXN], mark[MAXN], mark2[MAXN];
vector<PII> N[MAXN];

void dfs(int v, int lst, int height){
    mark[v] = 1;
    h[v] = height++;
    mnback[v] = st[v] = timer++;
    for (auto [u, e] : N[v]){
        if (!mark[u]){
            par[u][0] = v;
            for (int i = 1; i < LOG; i++){
                par[u][i] = par[par[u][i - 1]][i - 1];
            }
            dfs(u, e, height);
            if (mnback[u] > st[v]) boreshi[e] = 1;
            mnback[v] = min(mnback[v], mnback[u]);
        }
        else if (e != lst){
            mnback[v] = min(mnback[v], st[u]);
        }
    }
}

int balaaaaaa(int v, int k){
    for (int i = LOG - 1; i >= 0; i--){
        if (k >> i & 1){
            v = par[v][i];
        }
    }
    return v;
}

int LCA(int u, int v){
    if (h[u] > h[v]) swap(u, v);
    v = balaaaaaa(v, h[v] - h[u]);
    if (u == v) return v;
    for (int i = LOG - 1; i >= 0; i--){
        if (par[v][i] != par[u][i]){
            v = par[v][i], u = par[u][i];
        }
    }
    return par[u][0];
}

void dfs_ans(int v){
    mark2[v] = 1;
    for (auto [u, e] : N[v]){
        if (!mark2[u]){
            dfs_ans(u);
            psD[v] += psD[u], psU[v] += psU[u];
            if (boreshi[e] && (psD[u] || psU[u])){
                if ((jahat[e] == v && psD[u]) || (jahat[e] == u && psU[u])) ans[e] = 1;
                else ans[e] = 2;
            }
            else ans[e] = 3;
        }
    }
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1; i <= m; i++){
        int x, y; cin >> x >> y;
        N[x].PB({y, i}), N[y].PB({x, i});
        jahat[i] = x;
    }
    
    for (int i = 1; i <= n; i++){
        if (!mark2[i]){
            dfs_ans(i);
            for (int j = 0; j < LOG; j++){
                par[i][j] = i;
            }
            dfs(i, -1, 1);
        }
    }

    cin >> q;
    while (q--){
        int u, v; cin >> u >> v;
        int lca = LCA(u, v);
        psU[u]++, psU[lca]--;
        psD[v]++, psD[lca]--;
    }

    fill(mark2, mark2 + MAXN, 0);
    for (int i = 1; i <= n; i++){
        if (!mark2[i]){
            dfs_ans(i);
        }
    }

    for (int i = 1; i <= m; i++){
        if (ans[i] == 1) cout << 'R';
        else if (ans[i] == 2) cout << 'L';
        else cout << 'B';
    }
    return 0;
}

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