usaco2.1.1-----the castle（flood fill模型）

/*ID:lvfuan11PROG:castleLANG:C++translation:见usanocowsolution:flood fill的经典模型。dfs即可。注意题目要求选择最靠西边的墙，意味着同一个各自内，该格的北墙的优先级是比西墙高的！因为北墙更靠近西边。*/#include <iostream>#include <cstdio>#include <cstring>using namespace std;const int maxn = 55;const int dir_row[] = {-1, 1, 0, 0};const int dir_col[] = {0, 0, -1, 1};//上下左右int mat[maxn][maxn], n, m;int vis[maxn][maxn], area[maxn*maxn];bool wall[maxn][maxn][4];bool isWall(int r, int c, int d){if(d == 0 && mat[r][c] & 2)return true;if(d == 1 && mat[r][c] & 8)return true;if(d == 2 && mat[r][c] & 1)return true;if(d == 3 && mat[r][c] & 4)return true;return false;}inline bool inside(int x, int y){return x >= 0 && x < n && y >= 0 && y < m;}void dfs(int r, int c, int tag){vis[r][c] = tag;for(int d = 0; d < 4; d++) {int nr = r + dir_row[d];int nc = c + dir_col[d];if(inside(nr, nc) && vis[nr][nc] < 0 && !isWall(r, c, d))dfs(nr, nc, tag);}}int main(){freopen("castle.in", "r", stdin);freopen("castle.out", "w", stdout);    while(~scanf("%d%d", &m, &n)) {//n行m列memset(vis, -1, sizeof(vis));memset(wall, 0, sizeof(wall));for(int i = 0; i < n; i++) {for(int j = 0; j < m; j++) {scanf("%d", &mat[i][j]);}}int id = 0;for(int i = 0; i < n; i++) {for(int j = 0; j < m; j++) if(vis[i][j] < 0) {dfs(i, j, id++);}}int maxArea = 0;memset(area, 0, sizeof(area));for(int i = 0; i < n; i++) {for(int j = 0; j < m; j++) {area[vis[i][j]]++;maxArea = max(maxArea, area[vis[i][j]]);}}int ans = 0, row, col;char dir;for(int j = 0; j < m; j++) {//注意遍历的顺序for(int i = n-1; i >= 0; i--) {int currRoom = vis[i][j], northRoom = -1, eastRoom = -1;if(i > 0)northRoom = vis[i-1][j];if(j < m - 1)eastRoom = vis[i][j+1];if(northRoom != -1 && currRoom != northRoom && area[currRoom] + area[northRoom] > ans) {ans = area[currRoom] + area[northRoom];row = i;col = j;dir = 'N';}if(eastRoom != -1 && currRoom != eastRoom && area[currRoom] + area[eastRoom] > ans) {ans = area[currRoom] + area[eastRoom];row = i;col = j;dir = 'E';}}}printf("%d\n%d\n%d\n%d %d %c\n", id, maxArea, ans, row + 1, col + 1, dir);    }    return 0;}