Submission #536421

#	Time	Username	Problem	Language	Result	Execution time	Memory
536421		cig32	Valley (BOI19_valley)	C++17	36 / 100	946 ms	128616 KiB

valley

#include "bits/stdc++.h"
using namespace std;
const int MAXN = 2e5 + 10;
const int MOD = 120717661;
#define int long long
#define ll __int128
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
ll read() { // read int128
  int x; cin >> x; return (ll)x;
}
long long bm(long long b, long long p) {
  if(p==0) return 1 % MOD;
  long long r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
long long inv(long long b) { 
  return bm(b, MOD-2);
}
long long f[MAXN];
long long nCr(int n, int r) { 
  long long ans = f[n]; ans *= inv(f[r]); ans %= MOD;
  ans *= inv(f[n-r]); ans %= MOD; return ans;
}
void precomp() { 
  for(int i=0; i<MAXN; i++) f[i] = (i == 0 ? 1 % MOD : (f[i-1] * i) % MOD);
}

vector<pair<int, int> > adj[MAXN];

int oh[MAXN];
int shop[MAXN];
int x, y; // edge removed
vector<pair<int, int> > edges;
int dep[MAXN];
int tin[MAXN], tout[MAXN];
int par[MAXN];
int wow = 0;
vector<int> euler;
void dfs(int node, int prv, int cur) {
  oh[node] = 1e18;
  dep[node] = cur;
  tin[node] = ++wow;
  par[node] = prv;
  euler.push_back(node);
  for(auto x: adj[node]) {
    if(x.first != prv) {
      dfs(x.first, node, cur + x.second);
      oh[node] = min(oh[node], oh[x.first]);
      euler.push_back(node);
    }
  }
  tout[node] = ++wow;
  if(shop[node]) oh[node] = cur;
}

pair<int, int> st[14][MAXN];

int l[MAXN], r[MAXN];


int lca_idx(int x, int y) {
  int m1 = min(l[x], l[y]);
  int m2 = max(r[x], r[y]);
  int k = 32 - __builtin_clz(m2 - m1 + 1) - 1;
  return min(st[k][m1], st[k][m2 - (1<<k) + 1]).second;
}
void solve(int tc) {
  int n, s, q, e;
  cin >> n >> s >> q >> e;
  for(int i=1; i<n; i++) {
    int a, b, w;
    cin >> a >> b >> w;
    edges.push_back({a, b});
    adj[a].push_back({b, w});
    adj[b].push_back({a, w});
  }
  for(int i=0; i<s; i++) {
    int c; cin >> c;
    shop[c] = 1;
  }
  dfs(e, -1, 0);
  for(int i=0; i<euler.size(); i++) {
    st[0][i] = {dep[euler[i]], euler[i]};
  }
  for(int i=0; i<euler.size(); i++) r[euler[i]] = i;
  for(int i=euler.size() - 1; i>=0; i--) l[euler[i]] = i;
  for(int i=1; i<14; i++) {
    for(int j=0; j<euler.size(); j++) {
      if(j + (1<<i) - 1 < euler.size()) {
        st[i][j] = min(st[i-1][j], st[i-1][j + (1<<(i-1))]);
      }
    }
  }
  while(q--) {
    int i, r;
    cin >> i >> r;
    if(n == 1) {
      cout << "escaped\n";
      continue;
    }
    i--;
    x = edges[i].first, y = edges[i].second;
    if(tin[x] > tin[y]) swap(x, y);
    if(!(tin[y] <= tin[r] && tout[r] <= tout[y])) {
      cout << "escaped\n";
    }
    else {
      int ans = 1e18;
      for(int i=1; i<=n; i++) {
        if(tin[y] <= tin[i] && tout[i] <= tout[y]) {
          if(shop[i]) {
            ans = min(ans, dep[i] + dep[r] - 2 * dep[lca_idx(i, r)]);
          }
        }
      }
      cout << (ans == 1e18 ? "oo" : to_string(ans)) << "\n";
    }
  }

}
int32_t main(){
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; //cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}
/*
10 10 5 4
7 2 3
4 8 3
9 10 1
6 7 3
9 2 3
10 1 2
8 2 2
5 2 1
3 8 2
1 2 3 4 5 6 7 8 9 10
2 1
1 5
8 4
6 2
7 7
*/

Compilation message (stderr)

valley.cpp: In function 'void solve(long long int)':
valley.cpp:86:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   86 |   for(int i=0; i<euler.size(); i++) {
      |                ~^~~~~~~~~~~~~
valley.cpp:89:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   89 |   for(int i=0; i<euler.size(); i++) r[euler[i]] = i;
      |                ~^~~~~~~~~~~~~
valley.cpp:92:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   92 |     for(int j=0; j<euler.size(); j++) {
      |                  ~^~~~~~~~~~~~~
valley.cpp:93:25: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   93 |       if(j + (1<<i) - 1 < euler.size()) {
      |          ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 0 / 23
• Subtask 4: 0 / 41