백준 알고리즘 14716번 : 현수막

링크

https://www.acmicpc.net/problem/14716

sol1) BFS

#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define X first
#define Y second
#define pb push_back
#define fastio cin.tie(0)->sync_with_stdio(0)
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#define sz(v) (int)(v).size()
#define all(v) v.begin(), v.end()
#define rall(v) (v).rbegin(), (v).rend()
#define compress(v) sort(all(v)), (v).erase(unique(all(v)), (v).end())
#define OOB(x, y) ((x) < 0 || (x) >= m || (y) < 0 || (y) >= n)
#define debug(x) cout << (#x) << ": " << (x) << '\n'
using namespace std;
using ll = long long;
using ull = unsigned long long;
using dbl = double;
using ldb = long double;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using tii = tuple<int,int,int>;
template<typename T> using wector = vector<vector<T>>;

const int MOD = 1e9 + 7;
const int INF = 1e9 + 7;
const ll LNF = 1e18 + 7;

int adj[251][251];
bool vist[251][251];
int dx[] = { 1,-1,0,0,-1,1,-1,1 };
int dy[] = { 0,0,-1,1,-1,-1,1,1 };
int m,n;

void bfs(int x,int y){
  queue<pii> Q;
  Q.push({x, y});
  vist[x][y] = true;
  while(!Q.empty()){
    auto [curX,curY] = Q.front();
    Q.pop();
    for(int i = 0; i < 8; i++){
      auto nx = curX + dx[i];
      auto ny = curY + dy[i];
      if(OOB(nx, ny) || vist[nx][ny] || !adj[nx][ny]) continue;
      Q.push({nx, ny});
      vist[nx][ny] = true;
    }
  }
}

int main() {
	fastio;
  cin >> m >> n;
  for(int i = 0; i < m; i++){
    for(int j = 0; j < n; j++){
      cin >> adj[i][j];
    }
  }
  int components = 0;
  for(int i = 0; i < m; i++){
    for(int j = 0; j < n; j++){
      if(adj[i][j] && !vist[i][j]){
        bfs(i, j);
        components++;
      }
    }
  }
  cout << components << "\n";
	return 0;
}

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