Merge pull request neetcode-gh#1687 from a93a/1905

Create 1905-count-sub-islands.kt

kotlin/1905-count-sub-islands.kt

@@ -0,0 +1,37 @@
+class Solution {
+    fun countSubIslands(grid1: Array<IntArray>, grid2: Array<IntArray>): Int {
+
+        fun isValid(i: Int, j: Int) = i in (0 until grid2.size) && j in (0 until grid2[0].size) && grid2[i][j] == 1
+
+        val dir = arrayOf(
+            intArrayOf(1,0), 
+            intArrayOf(-1,0), 
+            intArrayOf(0,1), 
+            intArrayOf(0,-1)
+        )
+
+        fun dfs(i: Int, j: Int): Boolean {
+            if(grid1[i][j] != 1)
+                return false
+            grid2[i][j] = 0
+            var found = true
+            for((iD,jD) in dir){
+                val iN = i + iD
+                val jN = j + jD
+                if(isValid(iN, jN))
+                  found = found and dfs(iN, jN)
+            }
+            return found
+        }
+
+        var count = 0
+        for(i in 0 until grid1.size){
+            for(j in 0 until grid1[0].size){
+                if(grid1[i][j] == 1 && grid2[i][j] == 1)
+                    if(dfs(i, j) == true)
+                        count++
+            }
+        }            
+        return count
+    }
+}