Adding DiameterOfBinaryTree

Author: Sahilkumar19

DiameterOfBinaryTree.java

@@ -0,0 +1,66 @@
+/*
+Given the root of a binary tree, return the length of the diameter of the tree.
+The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.
+The length of a path between two nodes is represented by the number of edges between them.
+
+Example 1:
+Input: root = [1,2,3,4,5]
+Output: 3
+Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
+ */
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class DiameterOfBinaryTree {
+    public static void main(String[] args) {
+        TreeNode root=new TreeNode(1);
+        root.left=new TreeNode(2);
+        root.right=new TreeNode(3);
+        root.left.left=new TreeNode(4);
+        int ans = diameterOfBinaryTree(root);
+        System.out.println(ans);
+    }
+    public static int diameterOfBinaryTree(TreeNode root) {
+        List<Integer> result = new ArrayList<>();
+        if (root == null) {
+            return 0;
+        }
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.offer(root);
+
+        while (!queue.isEmpty()) {
+            int levelSize = queue.size();
+            for (int i = 0; i < levelSize; i++) {
+                TreeNode cur = queue.poll();
+
+                int leftDepth = maxDepth(cur.left);
+                int rightDepth = maxDepth(cur.right);
+                result.add(leftDepth + rightDepth);
+
+                if (cur.left != null) {
+                    queue.offer(cur.left);
+                }
+                if (cur.right != null) {
+                    queue.offer(cur.right);
+                }
+            }
+        }
+
+        int max = Integer.MIN_VALUE;
+        for (int num : result) {
+            if (num > max) {
+                max = num;
+            }
+        }
+        return max;
+    }
+
+    public static int maxDepth(TreeNode root) {
+        if (root == null) {
+            return 0;
+        }
+        return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
+    }
+}