LC#543 finds diameter of binary tree, recursively

Author: NirmalSilwal

Leetcode/easy/DiameterOfBinaryTree543.java

@@ -0,0 +1,54 @@
+package easy;
+
+public class DiameterOfBinaryTree543 {
+	public class TreeNode {
+		int val;
+		TreeNode left;
+		TreeNode right;
+
+		TreeNode() {
+		}
+
+		TreeNode(int val) {
+			this.val = val;
+		}
+
+		TreeNode(int val, TreeNode left, TreeNode right) {
+			this.val = val;
+			this.left = left;
+			this.right = right;
+		}
+	}
+
+	int ans = 0;
+
+	public int diameterOfBinaryTree(TreeNode root) {
+		if (root == null)
+			return 0;
+
+		if (root.left == null && root.right == null)
+			return 0;
+
+		int diameter = height(root.left) + height(root.right);
+		if (diameter > ans)
+			ans = diameter;
+
+		diameterOfBinaryTree(root.left);
+		diameterOfBinaryTree(root.right);
+
+		return ans;
+	}
+
+	private int height(TreeNode node) {
+		if (node == null)
+			return 0;
+
+		if (node.left == null && node.right == null)
+			return 1;
+
+		int lheight = 1 + height(node.left);
+		int rheight = 1 + height(node.right);
+
+		return Math.max(lheight, rheight);
+	}
+}