BOJ 24446 - 알고리즘 수업 - 너비 우선 탐색 3 [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());
  }
 
  vector<int> ans(n, -1);
  queue<pair<int, int>> q; q.push({r, 0});
 
  while (!q.empty()) {
    auto [cur, d] = q.front(); q.pop();
    if (~ans[cur]) continue;
    ans[cur] = d;
    for (int v : adj[cur]) {
      if (~ans[v]) continue;
      q.push({v, d+1});
    }
  }
 
  for (int i=0; i<n; i++) {
    cout << ans[i] << "\n";
  }
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}