437. Path Sum III

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

Find the number of paths that 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 only from parent nodes to child nodes).

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

 - 列表内容/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     struct TreeNode *left; *     struct TreeNode *right; * }; */int pathSumRoot(struct TreeNode* root,int sum) {    int count = 0;    if(root == NULL){        return count;    }    if(root->val == sum){        count++;    }     /*left node*/    if(root->left){        count += pathSumRoot(root->left,sum-root->val);    }    /*right node*/    if(root->right){        count += pathSumRoot(root->right,sum-root->val);    }    return count;}int pathSum(struct TreeNode* root, int sum) {    int count = 0;    if(root == NULL){        return 0;    }    if(root->left == NULL && root->right == NULL){        if(root->val == sum){            return 1;        }else{            return 0;        }    }    return pathSumRoot(root,sum) + pathSum(root->left,sum) + pathSum(root->right,sum);}