题目:
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] ]
解题思路:用DFS算法进行搜索,搜索到叶子节点并且路径和等于设定值时,将路径存入容器。
代码:
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<vector<int> > pathSum(TreeNode *root, int sum) {
vector<vector<int>> Path;
vector<int> CurrPath;
build_path(Path, CurrPath, root, sum);
return Path;
}
private:
void build_path(vector<vector<int>> &Path,vector<int> &CurrPath, TreeNode *root, int sum){
if(!root)return;
CurrPath.push_back(root->val);
if(!root->left&&!root->right){
if(root->val==sum)Path.push_back(CurrPath);
}else{
build_path(Path,CurrPath,root->left,sum-root->val);
build_path(Path,CurrPath,root->right,sum-root->val);
}
CurrPath.pop_back();
}
};