Create 1254.cpp

Author: JanaSabuj

1254/1254.cpp

@@ -0,0 +1,55 @@
+class Solution {
+public:
+    int dx[4] = {0, 0, 1, -1};
+    int dy[4] = {1, -1, 0, 0};
+    bool valid(int r, int c, int n, int m){
+        return (r >= 0 and r < n and c >= 0 and c < m);
+    }
+    void dfs(vector<vector<int>>& grid, int i, int j, int n, int m){
+        grid[i][j] = 1;
+        for(int k = 0; k < 4; k++){
+            int r = i + dx[k];
+            int c = j + dy[k];
+            
+            if(valid(r, c, n, m) and grid[r][c] == 0)
+                dfs(grid, r, c, n, m);
+        }
+    }
+    
+    void dfs2(vector<vector<int>>& grid, int i, int j, int n, int m){
+        grid[i][j] = 1;
+        for(int k = 0; k < 4; k++){
+            int r = i + dx[k];
+            int c = j + dy[k];
+            
+            if(valid(r, c, n, m) and grid[r][c] == 0)
+                dfs2(grid, r, c, n, m);
+        }
+    }
+    
+    int closedIsland(vector<vector<int>>& grid) {
+        int n = grid.size();
+        int m = grid[0].size();
+        
+        for(int i = 0; i < n; i++){
+            for(int j = 0; j < m; j++){
+                if(grid[i][j] == 0 and (i == 0 || i == n-1 || j == 0 || j == m-1)){
+                    dfs(grid, i, j, n, m);
+                }
+            }
+        }
+        
+        int cnt = 0;
+        for(int i = 0; i < n; i++){
+            for(int j = 0; j < m; j++){
+                if(grid[i][j] == 0){
+                    cnt++;
+                    dfs2(grid, i, j, n, m);
+                }                    
+            }
+        }
+        
+        return cnt;
+        
+    }
+};