Create 1020-number-of-enclaves.kt

Author: a93a

Diff for: kotlin/1020-number-of-enclaves.kt

@@ -0,0 +1,52 @@
+class Solution {
+    fun numEnclaves(grid: Array<IntArray>): Int {
+        val rows = grid.size
+        val cols = grid[0].size
+        val dirs = arrayOf(
+            intArrayOf(1, 0),
+            intArrayOf(-1, 0),
+            intArrayOf(0, 1),
+            intArrayOf(0, -1)
+        )
+
+        val visited = Array(rows){BooleanArray(cols)}
+
+        fun isValid(r: Int, c: Int) = 
+            r in (0 until rows) && 
+            c in (0 until cols) && 
+            visited[r][c] == false && 
+            grid[r][c] == 1
+
+        fun isValidBorder(r: Int, c: Int) = 
+            (r == 0 || r == rows - 1 || c == 0 || c == cols - 1) && 
+            visited[r][c] == false
+
+        fun dfs(r: Int, c: Int): Int {
+            if (!isValid(r, c))
+                return 0
+            
+            visited[r][c] = true
+
+            var res = 1
+            for ((dr, dc) in dirs) {
+                res += dfs(r + dr, c + dc)
+            }
+
+            return res
+        }
+
+        var totalLand = 0
+        var borderLand = 0
+        for (r in 0 until rows) {
+            for (c in 0 until cols) {
+                totalLand += grid[r][c]
+                if (grid[r][c] == 1 && isValidBorder(r, c)) {
+                    borderLand += dfs(r, c)
+                }
+            }
+        }
+
+        return totalLand - borderLand
+    }
+
+}