每日一题洛谷P8662 [蓝桥杯 2018 省 AB] 全球变暖c++

P8662 [蓝桥杯 2018 省 AB] 全球变暖 - 洛谷 (luogu.com.cn)

DFS

#include<iostream>
using namespace std;
char a[1001][1001];
bool s[1001][1001];
int res = 0;
int n;
bool flag = true;
int dx[4] = { -1,0,1,0 };
int dy[4] = { 0,-1,0,1 };
void dfs(int x, int y) {s[x][y] = true;bool safe = true;for (int i = 0; i < 4; i++) {int nx = x + dx[i];int ny = y + dy[i];if (nx<1 || ny>n || ny<1 || nx>n || a[nx][ny] == '.') {safe = false;break;}}if (safe)flag = true;for (int i = 0; i < 4; i++) {int nx = x + dx[i];int ny = y + dy[i];if (nx >= 1 && nx <= n && ny >= 1 && ny <= n && a[nx][ny] == '#' && !s[nx][ny]) {dfs(nx, ny);}}
}
int  main() {cin >> n;for (int i = 1; i <= n; i++) {for (int j = 1; j <= n; j++) {cin >> a[i][j];}}for (int i = 1; i <= n; i++) {for (int j = 1; j <= n; j++) {if (a[i][j] == '#' && !s[i][j]) {flag = false;dfs(i, j);if (!flag)res++;}flag = false;}}cout << res;return 0;
}