113:Path Sum II【樹】【DFS】

題目鏈接：click~

/*題意：給出一顆樹和一個值sum，求樹中從根結點到葉子結點的所有路徑 
        且每條路徑上結點的和等於sum   */  
class Solution {
public:
    void GetPathSum(TreeNode *T, int sum, vector<int> &v, vector<vector<int>> &path) {
        if(T == NULL) return;

        //當前結點是葉子結點，且結點值等於sum
        if(T->left == NULL && T->right == NULL && T->val == sum) {
            v.push_back(T->val);
            path.push_back(v);
            v.pop_back();
            return;
        }
        v.push_back(T->val);

        int next_sum = sum - T->val;
        GetPathSum(T->left, next_sum, v, path);
        GetPathSum(T->right, next_sum, v, path);
        v.pop_back();

    }
    vector<vector<int> > pathSum(TreeNode *root, int sum) {
        vector<vector<int>> path;
        vector<int> v;//存放每一個可能的路徑
        GetPathSum(root, sum, v, path);
        return path;
    }
};