Submission #875540

#	Time	Username	Problem	Language	Result	Execution time	Memory
875540		NeroZein	Fireworks (APIO16_fireworks)	C++17	0 / 100	0 ms	348 KiB

fireworks

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

#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif

const int N = 5003;

long long dis[N]; 
long long mn[N], mx[N]; 
vector<pair<int, int>> g[N]; 

void dfs(int v) {
  if (g[v].size() == 0) {
    mn[v] = mx[v] = dis[v];
    return; 
  }
  mn[v] = LLONG_MAX;
  mx[v] = -LLONG_MAX;
  for (auto [u, w] : g[v]) {
    dis[u] = dis[v] + w; 
    dfs(u); 
    mn[v] = min(mn[v], mn[u]);
    mx[v] = max(mx[v], mx[u]);
  }
}

long long dfs2(int v, long long sub, const long long req) {
  long long ret = 0;
  for (auto [u, w] : g[v]) {
    long long t = 0, r = 1; 
    if (mn[u] - sub > req) {
      t = min((long long) w, mn[u] - sub - req); 
    } else if (mx[u] - sub < req) {
      t = min((long long) w, req - (mx[u] - sub)); 
      r = -1; 
    }
    ret += t + dfs2(u, sub + t * r, req); 
  }
  return ret;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, m;
  cin >> n >> m;
  for(int i = 2; i <= n + m; ++i) {
    int p, c;
    cin >> p >> c;
    g[p].emplace_back(i, c); 
  }
  dfs(1); 
  long long ans = LLONG_MAX; 
  for (int i = n + 1; i <= n + m; ++i) {
    ans = min(ans, dfs2(1, 0, dis[i])); 
    //deb(dis[i]) deb(dfs2(1, 0, dis[i])) cout << '\n';
  }
  cout << ans << '\n'; 
  return 0;
}

• Subtask 1: 0 / 7
• Subtask 2: 0 / 19
• Subtask 3: 0 / 29
• Subtask 4: 0 / 45