Submission #1106744

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106744		fryingduc	Hotspot (NOI17_hotspot)	C++17	100 / 100	571 ms	1360 KiB

hotspot

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

#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif

const int maxn = 5005;
int n, m, k;
vector<int> g[maxn];

int d[maxn], rev_d[maxn];
long long cnt[maxn], rev_cnt[maxn];

long double f[maxn];
  
void bfs(int src, int d[], long long cnt[]) {
  for(int i = 1; i <= n; ++i) {
    d[i] = 1e9;
    cnt[i] = 0;
  }
  queue<int> q;
  q.push(src);
  d[src] = 0, cnt[src] = 1;
  while(!q.empty()) {
    int u = q.front();
    q.pop();
    for(auto v:g[u]) {
      if(d[v] > d[u] + 1) {
        d[v] = d[u] + 1;
        cnt[v] = cnt[u];
        q.push(v);
      }
      else if(d[v] == d[u] + 1) {
        cnt[v] += cnt[u];
      }
    }
  }  
}
void solve() {
  cin >> n >> m;
  for(int i = 1; i <= m; ++i) {
    int u, v; cin >> u >> v;
    ++u, ++v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  int q; cin >> q;
  while(q--) {
    int u, v; cin >> u >> v;
    ++u, ++v;
    bfs(u, d, cnt);
    bfs(v, rev_d, rev_cnt);
    
    for(int i = 1; i <= n; ++i) {
      if(d[i] + rev_d[i] == d[v]) {
        f[i] += (1.0 * cnt[i] * rev_cnt[i]) / cnt[v];
      }
    }
  }
  
  int res = 0;
  for(int i = 1; i <= n; ++i) {
    if(res == 0 || f[res] < f[i]) res = i;
  }
  cout << res - 1;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  solve();

  return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 11 / 11
• Subtask 4: 18 / 18
• Subtask 5: 26 / 26
• Subtask 6: 36 / 36