Implement Maximum Path Sum in a binary tree

Author: harshithasudhakar

Binary Tree/Problems/MaximumPathSum.java

@@ -0,0 +1,33 @@
+/**
+ * Definition for a binary tree node.
+ * 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;
+ *     }
+ * }
+ */
+class MaximumPathSum {
+    int maxSum = Integer.MIN_VALUE;
+    public int maxPathSum(TreeNode root) {
+        postorder(root);
+        return maxSum;
+    }
+
+    int postorder(TreeNode node){
+        if(node == null){
+            return 0;
+        }
+
+        int left = postorder(node.left);
+        int right = postorder(node.right);
+        maxSum = Math.max(maxSum, node.val+Math.max(0,left)+Math.max(0,right));
+        return node.val+Math.max(Math.max(0,left), Math.max(0,right));
+    }
+}