Add 437_Path_Sum_III.java

Author: Sean Prashad

Tree Depth First Search/437_Path_Sum_III.java

@@ -0,0 +1,22 @@
+class Solution {
+ public int pathSum(TreeNode root, int sum) {
+ if (root == null) {
+ return 0;
+ }
+
+ return traverseSubtree(root, sum) + pathSum(root.left, sum) + pathSum(root.right, sum);
+ }
+
+ private int traverseSubtree(TreeNode root, int sum) {
+ int result = 0;
+ if (root == null) {
+ return result;
+ }
+
+ if (root.val == sum) {
+ ++result;
+ }
+
+ return result + traverseSubtree(root.left, sum - root.val) + traverseSubtree(root.right, sum - root.val);
+ }
+}