面试题25：二叉树中和为某一值的路径

/*
struct TreeNode {
int val;
struct TreeNode *left;
struct TreeNode *right;
TreeNode(int x) :
val(x), left(NULL), right(NULL) {
}
};*/
class Solution {
public:
vector<vector<int> > FindPath(TreeNode* root,int expectNumber) {
vector<vector<int>> result;
if(!root)
return result;
vector<int> trace;
find(root, expectNumber, trace, result);
return result;
}
void find(TreeNode* root, int expectNumber, vector<int>& trace, vector<vector<int>>& result){
trace.push_back(root->val);
if(!root->left && !root->right){
if(root->val == expectNumber)
result.push_back(trace);
}
if(root->left){
find(root->left, expectNumber - root->val, trace, result);
}
if(root->right){
find(root->right, expectNumber - root->val, trace, result);
}
trace.pop_back();
}
};