Submission #695074

#	Time	Username	Problem	Language	Result	Execution time	Memory
695074		ShaShi	One-Way Streets (CEOI17_oneway)	C++17	100 / 100	127 ms	30152 KiB

oneway

/** This is the end ... **/
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define int long long int
#define dint long double
#define endl "\n"
#define pii pair<int, int>
#define pb push_back
#define F first
#define S second

using namespace std;

const int MOD = (int)1e9 + 7;
const int MAXN = (int)2e5 + 23;
const int MAXK = (int)40000 + 23;
const int MAX_LOG = 23;
const int PRM = (int)31622 + 23;
const int INF = (int)9e9;

int POW(int x, int y) {
    return (!y ? 1 : (y & 1 ? x * POW(x * x % MOD, y / 2) % MOD : POW(x * x % MOD, y / 2) % MOD));
}

int n, m, s, q, t, tmp, tmp2, cmp, u, v, u2, v2, ans1, ans2, k, flag, l, r, mid;
int arr[MAXN], cnt[MAXN], h[MAXN], seen[MAXN], pow2dad[MAXN][MAX_LOG], cnt2[MAXN], dad[MAXN], bala[MAXN], payin[MAXN], bkedge[MAXN];
vector<pii> g[MAXN];
vector<pii> edges;
vector<int> vec, e[MAXN];

int num[MAXN], low[MAXN], ti, comp[MAXN], w[MAXN];
 
void dfs(int u, int p) {
     vec.push_back(u);
     low[u] = num[u] = ++ti;
     for (int i = 0; i < g[u].size(); ++i) {
          int v = g[u][i].first;
          int id = g[u][i].second;
          if (id == p) continue;
          if (comp[v]) continue;
          if (!num[v]) {
               dfs(v, id);
               low[u] = min(low[u], low[v]);
          } else low[u] = min(low[u], num[v]);
     }
     if (low[u] == num[u]) {
          ++m;
          while (vec.size()) {
               int v = vec.back();
               vec.pop_back();
               comp[v] = m;
               for (auto w: g[v]) {
                    if (comp[w.first] && m != comp[w.first]) e[m].push_back(comp[w.first]);
               }
               if (v == u) break;
          }
     }
}
 
void pull(int u) {
     num[u] = 1;
     for (auto v: e[u]) {
          if (!num[v]) pull(v);
          w[u] += w[v];
     }
}


int32_t main() {
     ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);

     cin >> n >> m;

     for (int i=1; i<=m; i++) {
          cin >> u >> v;

          edges.pb({u, v});

          g[u].pb({v, i});
          g[v].pb({u, i});
     }

     for (int i = 1; i <= n; ++i) {
          if (num[i]) continue;
          dfs(i, 0);
     }
     cin >> q;
     while (q--) {
          int u, v;
          cin >> u >> v;
          u = comp[u], v = comp[v];
          if (u == v) continue;
          ++w[u], --w[v];
     }
     memset(num, 0, sizeof(num));
     for (int i = 1; i <= m; ++i) {
          if (num[i]) continue;
          pull(i);
     }
     for (int i = 0; i < edges.size(); ++i) {
          int u = edges[i].first;
          int v = edges[i].second;
          u = comp[u], v = comp[v];
          if (u == v) {
               cout << 'B';
               continue;
          }
          if (u > v) {
               if (w[v] < 0) cout << 'R';
               if (w[v] > 0) cout << 'L';
               if (w[v] == 0) cout << 'B';
          } else {
               if (w[u] < 0) cout << 'L';
               if (w[u] > 0) cout << 'R';
               if (w[u] == 0) cout << 'B';
          }
     }




     return 0;
}

Compilation message (stderr)

oneway.cpp: In function 'void dfs(long long int, long long int)':
oneway.cpp:37:24: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |      for (int i = 0; i < g[u].size(); ++i) {
      |                      ~~^~~~~~~~~~~~~
oneway.cpp: In function 'int32_t main()':
oneway.cpp:101:24: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |      for (int i = 0; i < edges.size(); ++i) {
      |                      ~~^~~~~~~~~~~~~~

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