Count Good Nodes in Binary Tree - Recursive

Author: dksifoua

src/main/java/io/dksifoua/leetcode/countgoodnodesinbinarytree/Solution.java

@@ -31,4 +31,23 @@ public int goodNodes(TreeNode root) {
 
         return result;
     }
+
+    public int goodNodesRecursive(TreeNode root) {
+        int[] result = new int[] { 0 };
+        if (root == null) return result[0];
+
+        dfs(root, Integer.MIN_VALUE, result);
+
+        return result[0];
+    }
+
+    private void dfs(TreeNode node, int maxValue, int[] result) {
+        if (node.getValue() >= maxValue) {
+            maxValue = node.getValue();
+            result[0] += 1;
+        }
+
+        if (node.getLeft() != null) dfs(node.getLeft(), maxValue, result);
+        if (node.getRight() != null) dfs(node.getRight(), maxValue, result);
+    }
 }

src/test/java/io/dksifoua/leetcode/countgoodnodesinbinarytree/SolutionTest.java

@@ -1,7 +1,6 @@
 package io.dksifoua.leetcode.countgoodnodesinbinarytree;
 
 import io.dksifoua.leetcode.utils.TreeNode;
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -15,13 +14,28 @@ void test1() {
         assertEquals(4, solution.goodNodes(TreeNode.build(new Integer[] { 3, 1, 4, 3, null, 1, 5 })));
     }
 
+    @Test
+    void test1Recursive() {
+        assertEquals(4, solution.goodNodesRecursive(TreeNode.build(new Integer[] { 3, 1, 4, 3, null, 1, 5 })));
+    }
+
     @Test
     void test2() {
         assertEquals(3, solution.goodNodes(TreeNode.build(new Integer[] { 3, 3, null, 4, 2 })));
     }
 
+    @Test
+    void test2Recursive() {
+        assertEquals(3, solution.goodNodesRecursive(TreeNode.build(new Integer[] { 3, 3, null, 4, 2 })));
+    }
+
     @Test
     void test3() {
         assertEquals(1, solution.goodNodes(TreeNode.build(new Integer[] { 1 })));
     }
+
+    @Test
+    void test3Recursive() {
+        assertEquals(1, solution.goodNodesRecursive(TreeNode.build(new Integer[] { 1 })));
+    }
 }