[LeetCode] Path Sum II
Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.
For example:Given the below binary tree and
sum = 22
,
5 / \ 4 8 / / \ 11 13 4 / \ / \ 7 2 5 1
return
[ [5,4,11,2], [5,8,4,5] ]
Tree Depth-first Search
思路:dfs,递归,注意标红的语句
/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { vector<vector<int> > m_res; vector<int> m_vec; public: void dfs(TreeNode * root, int sum) { if(root == NULL) return; if(root->left == NULL && root->right == NULL) { if(root->val == sum) { m_vec.push_back(root->val); m_res.push_back(m_vec); m_vec.pop_back(); } return; } m_vec.push_back(root->val); if(root->left) { dfs(root->left, sum-root->val); } if(root->right) { dfs(root->right, sum-root->val); } m_vec.pop_back(); } vector<vector<int> > pathSum(TreeNode *root, int sum) { m_vec.clear(); m_res.clear(); dfs(root, sum); return m_res; } };