BOJ 24447 - 알고리즘 수업 - 너비 우선 탐색 4 [C++]

문제

링크

풀이

#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>
using namespace std;
 
void solve(void) {
  int n, m, r; cin >> n >> m >> r; r--;
  vector<vector<int>> adj(n);
  while (m--) {
    int u, v; cin >> u >> v; u--; v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
 
  for (int i=0; i<n; i++) {
    sort(adj[i].begin(), adj[i].end());
  }
 
  long long idx = 1;
  vector<long long> a(n, -1);
  queue<pair<int, long long>> q; q.push({r, 0});
 
  while (!q.empty()) {
    auto [cur, d] = q.front(); q.pop();
    if (~a[cur]) continue;
    a[cur] = d * idx++;
    for (int v : adj[cur]) {
      if (~a[v]) continue;
      q.push({v, d+1});
    }
  }
 
  long long ans = 0;
  for (int i=0; i<n; i++) {
    if (~a[i]) ans += a[i];
  }
  cout << ans;
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}