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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.
For example,
1 / 2 3
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Return the sum = 12 + 13 = 25.
1 int sumNumbers(TreeNode *root) 2 { 3 int total_sum = 0; 4 int path_sum = 0; 5 stack<TreeNode *> node_stack; 6 TreeNode *visit = root, *last_visit = NULL, *peek = NULL; 7 8 while (!node_stack.empty() || (visit != NULL)) 9 { 10 if (visit != NULL) 11 { 12 path_sum = path_sum * 10 + visit->val; 13 if ((visit->left == NULL) && (visit->right == NULL)) // leaf node 14 { 15 total_sum += path_sum; 16 } 17 node_stack.push(visit); 18 visit = visit->left; 19 } 20 else 21 { 22 peek = node_stack.top(); 23 if (peek->right != NULL && peek->right != last_visit) 24 { 25 visit = peek->right; 26 } 27 else 28 { 29 node_stack.pop(); 30 last_visit = peek; 31 path_sum /= 10; 32 } 33 } 34 } 35 36 return total_sum; 37 }
leetcode 129. Sum Root to Leaf Numbers
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原文地址：http://www.cnblogs.com/ym65536/p/4263706.html
