練習問題
島を数える†
問題文
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);++i)
// 四方の定義
int dx[] = { -1, 0, 1, 0 };
int dy[] = { 0, -1, 0, 1 };
using v = vector<bool>;
using vv = vector<v>;
// 深さ優先で島を消していく
inline
void dfs(vv&f, int i, int j, int h, int w) {
if (i < 0 or j < 0 or i >= h or j >= w) return;
if (not f[i][j]) return;
f[i][j] = false;
rep (k, 4) {
dfs(f, i + dx[k], j + dy[k], h, w);
}
}
int main() {
int h, w; cin >> h >> w;
vv f(h, v(w)); // f[i][j] = ((i, j) が陸なら true)
rep (i, h) {
string s; cin >> s;
rep (j, w) { f[i][j] = s[j] == '#'; }
}
int ans = 0;
rep (i, h) {
rep (j, w) {
if (f[i][j]) {
++ans;
dfs(f, i, j, h, w);
}
}
}
cout << ans << endl;
return 0;
}
