【HDOJ】3329 The Flood

超简单BFS。

 /* 3329 */
 #include <iostream>
 #include <queue>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 using namespace std;

 #define MAXN 105

 typedef struct node_t {
     int x, y;
     node_t() {}
     node_t(int xx, int yy) {
         x = xx; y = yy;
     }
 } node_t;

 int n, m, h, total;
 int map[MAXN][MAXN];
 bool visit[MAXN][MAXN];
 int dir[][] = {
     -,,,,,-,,
 };

 inline bool check(int x, int y) {
     return x< || x>=n || y< || y>=m;
 }

 void border_bfs(int x, int y) {
     int i, j, k;
     int xx, yy;
     queue<node_t> Q;
     node_t nd;

     Q.push(node_t(x, y));
     visit[x][y] = true;

     while (!Q.empty()) {
         nd = Q.front();
         Q.pop();
         --total;
         for (i=; i<; ++i) {
             xx = nd.x + dir[i][];
             yy = nd.y + dir[i][];
             if (check(xx, yy) || visit[xx][yy] || map[xx][yy]>h)
                 continue;
             visit[xx][yy] = true;
             Q.push(node_t(xx, yy));
         }
     }
 }

 void bfs(int x, int y) {
     int xx, yy, s;
     int i, j, k;
     queue<node_t> Q;
     node_t nd;

     Q.push(node_t(x, y));
     visit[x][y] = true;

     while (!Q.empty()) {
         nd = Q.front();
         Q.pop();
         --total;
         for (i=; i<; ++i) {
             xx = nd.x + dir[i][];
             yy = nd.y + dir[i][];
             if (check(xx,yy) || visit[xx][yy])
                 continue;
             visit[xx][yy] = true;
             Q.push(node_t(xx, yy));
         }
     }
 }

 int main() {
     int t = ;
     int i, j, k, tmp;
     bool flag;
     int maxh;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     while (scanf("%d %d",&n,&m)!=EOF && (n||m)) {
         maxh = -;
         for (i=; i<n; ++i) {
             for (j=; j<m; ++j) {
                 scanf("%d", &map[i][j]);
                 if (map[i][j] > maxh)
                     maxh = map[i][j];
             }
         }
         tmp = n*m;
         for (h=; h<maxh; ++h) {
             // handle border of map
             total = tmp;
             memset(visit, false, sizeof(visit));
             for (j=; j<m; ++j) {
                 if (!visit[][j] && map[][j]<=h)
                     border_bfs(, j);
                 if (!visit[n-][j] && map[n-][j]<=h)
                     border_bfs(n-, j);
             }
             for (i=; i<n; ++i) {
                 if (!visit[i][] && map[i][]<=h)
                     border_bfs(i, );
                 if (!visit[i][m-] && map[i][m-]<=h)
                     border_bfs(i, m-);
             }
             // check if there exsits two or more lands
             flag = false;
             for (i=; i<n; ++i) {
                 for (j=; j<m; ++j) {
                     if (!visit[i][j]) {
                         flag = true;
                         break;
                     }
                 }
                 if (flag)
                     break;
             }
             if (flag) {
                 bfs(i, j);
                 if (total > )
                     break;
             }
         }
         if (h < maxh)
             printf("Case %d: Island splits when ocean rises %d feet.\n", ++t, h);
         else
             printf("Case %d: Island never splits.\n", ++t);
     }

     return ;
 }