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problem:
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]
]
------------------------------------------------------------------------------------
solution:
// Definition for binary tree
struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
void pathSum_aux(TreeNode *root, int sum, vector<vector<int> > &ret, vector<int> &tmp)
{
if(root == NULL)
return;
tmp.push_back(root->val);
int leftsum = sum - root->val;
if(leftsum == 0 && root->left == NULL && root->right == NULL)
{
ret.push_back(tmp);
}
pathSum_aux(root->left, leftsum, ret, tmp);
pathSum_aux(root->right, leftsum, ret, tmp);
tmp.pop_back();
}
vector<vector<int> > pathSum(TreeNode *root, int sum)
{
vector<vector<int> > ret;
if(root == NULL)
return ret;
vector<int> tmp;
pathSum_aux(root, sum, ret, tmp);
return ret;
}