leetcode:437. Path Sum III

You is given a binary tree in which each node contains an integer value.

Find the number of paths this sum to a given value.

The path does not need-to-start or end at the root or a leaf, but it must go downwards (traveling with from parent nodes T o child nodes).

The tree has no more than nodes and the values is in the range-1,000,000 to 1,000,000.

Example:

root = [Ten,5,-3,3,2,NULL, One,3,-2,NULL,1], sum =8      Ten/      5-3/ \      3   2    One/ \   3-2   1Return3. The paths, sum to8is :1.5-32.5-2-13. -3- One

Given a binary tree, find the path and the number of paths equal to sum. The path here refers to the path from the parent node to the child node, not necessarily from the root node to the leaf node. Think of depth-first search immediately, but note that the path does not necessarily start at the root node. So for a parent node, the path on the path that meets the requirements of the problem should include the path in the left and right subtrees and the path to sum in addition to the path in the left and right subtree and the path to Sum-root->val.

/** Definition for a binary tree node. * struct TreeNode {* int val; * TreeNode *left; * TreeNode *right; * TreeNode (int x): Val (x), left (null), right (NULL) {} *}; */classSolution { Public:    intPathsum (treenode* root,intsum) {        if(!root)return 0; returnPathsum (root->left,sum) +pathsum (root->right,sum) +Pathsumroot (root,sum); }        intPathsumroot (treenode* root,intsum) {        if(!root)return 0; intCount= (sum==root->val?1:0); returnPathsumroot (Root->left,sum-root->val) + pathsumroot (root->right,sum-root->val) +count; }};

leetcode:437. Path Sum III