Path Sum III

啊这个递归总是会加重或者少加，办法就是你写出来那个过程，就知道哪里重了哪里少加了........

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: int pathSum(TreeNode* root, int sum) { if(root==NULL) return 0; return pathThis(root,sum)+pathSum(root->left,sum)+pathSum(root->right,sum); } int pathThis(TreeNode* root,int sum){ if(root==NULL) return 0; int temp=0; if(root->val==sum) temp+=1; return temp+pathThis(root->left,sum-root->val)+ pathThis(root->right,sum-root->val); } };