Time: 2756 ms (5.07%), Space: 118.6 MB (26.09%) - LeetHub

Author: knockcat

1905-count-sub-islands/1905-count-sub-islands.cpp

@@ -0,0 +1,69 @@
+class Solution {
+public:
+    int countSubIslands(vector<vector<int>>& grid1, vector<vector<int>>& grid2) {
+        
+        int n = grid1.size();
+        int m = grid1[0].size();
+        
+        vector<vector<bool>> visited(n, vector<bool>(m, false)), visited2(n, vector<bool>(m, false));
+        
+        function<void(int, int)> dfs = [&](int i, int j)
+        {
+            if(i < 0 or j < 0 or i >= n or j >= m or visited[i][j] or !grid1[i][j])
+                return;
+            
+            visited[i][j] = 1;
+            
+            dfs(i-1, j);
+            dfs(i, j+1);
+            dfs(i+1, j);
+            dfs(i, j-1);
+        };
+        
+        for(int i = 0; i < n; ++i)
+        {
+            for(int j = 0; j < m; ++j)
+            {
+                if(!visited[i][j] and grid1[i][j])
+                    dfs(i, j);
+            }
+        }
+        
+        function<bool(int, int)> dfs2 = [&](int i, int j) -> bool{
+            if(i < 0 or j < 0 or i >= n or j >= m or visited2[i][j] or !grid2[i][j])
+                return true;
+            
+            if(!visited[i][j]) return false;
+            
+            visited2[i][j] = true;
+            
+            bool up, left, right, down;
+            up = left = right = down = true;
+            
+            up = dfs2(i-1, j);
+            left = dfs2(i, j-1);
+            down = dfs2(i+1, j);
+            right = dfs2(i, j+1);
+            
+            return up and left and down and right;
+        };
+        
+        int subIsland = 0;
+        
+        for(int i = 0; i < n; ++i)
+        {
+            for(int j = 0; j < m; ++j)
+            {
+                if(!visited2[i][j] and grid2[i][j])
+                {
+                    if(dfs2(i, j))
+                    {
+                        ++subIsland;
+                    }
+                }
+            }
+        }
+        
+        return subIsland;
+    }
+};