2 Tree solutions in Java: Problem 100 & 124

371-Sum-of-Two-Integers.java

@@ -7,4 +7,4 @@ public int getSum(int a, int b) {
         }
         return a;
     }
-}
+}

java/100-Same-Tree.java

@@ -0,0 +1,40 @@
+package java;
+
+/**
+ * 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 Solution {
+    public boolean isSameTree(TreeNode p, TreeNode q) {
+        return dfs(p, q);
+    }
+
+    private boolean dfs(TreeNode p, TreeNode q) {
+        if (p == null && q == null) {
+            return true;
+        }
+
+        if (p == null || q == null) {
+            return false;
+        }
+
+        if (p.val != q.val) return false;
+
+        boolean left = dfs(p.left, q.left);
+        boolean right = dfs(p.right, q.right);
+
+        return left && right;
+    }
+}
+

java/124-Binary-Tree-Maximum-Path-Sum.java

@@ -0,0 +1,43 @@
+package java;
+
+/**
+ * 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 Solution {
+
+    int[] res = new int[1];
+
+    public int maxPathSum(TreeNode root) {
+        res[0] = root.val;
+        dfs(root);
+        return res[0];
+    }
+
+    private int dfs(TreeNode node) {
+        if (node == null) return 0;
+
+        int leftMax = dfs(node.left);
+        int rightMax = dfs(node.right);
+
+        leftMax = Math.max(leftMax, 0);
+        rightMax = Math.max(rightMax, 0);
+
+        int allMax = leftMax + rightMax + node.val;
+        res[0] = Math.max(res[0], allMax);
+
+
+        return node.val + Math.max(leftMax, rightMax);
+    }
+}

java/21-Merge-Two-Sorted-Lists.java

@@ -1,3 +1,5 @@
+package java;
+
 /**
  * Definition for singly-linked list.
  * public class ListNode {