Sum Root to Leaf Numbers

Author: ishpreet-singh

26.cpp

@@ -0,0 +1,54 @@
+/*
+
+Sum Root to Leaf Numbers
+------------------------
+
+Solution
+Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.
+
+An example is the root-to-leaf path 1->2->3 which represents the number 123.
+
+Find the total sum of all root-to-leaf numbers.
+
+Note: A leaf is a node with no children.
+
+Example:
+
+Input: [1,2,3]
+    1
+   / \
+  2   3
+Output: 25
+Explanation:
+The root-to-leaf path 1->2 represents the number 12.
+The root-to-leaf path 1->3 represents the number 13.
+Therefore, sum = 12 + 13 = 25.
+Example 2:
+
+Input: [4,9,0,5,1]
+    4
+   / \
+  9   0
+ / \
+5   1
+Output: 1026
+Explanation:
+The root-to-leaf path 4->9->5 represents the number 495.
+The root-to-leaf path 4->9->1 represents the number 491.
+The root-to-leaf path 4->0 represents the number 40.
+Therefore, sum = 495 + 491 + 40 = 1026.
+
+*/
+
+class Solution {
+public:
+    int sumNumbers(TreeNode* root) {
+        return getSum(root, 0);
+    }
+    int getSum(TreeNode *node, int sum) {
+        if (node == NULL) return 0;
+		int current_sum = sum * 10 + node->val;
+        if (node->left == NULL && node->right == NULL) return current_sum;
+        return getSum(node->left, current_sum) + getSum(node->right, current_sum);
+    }
+};