113. Path Sum II

T

Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.

S

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void resultPathSum(TreeNode* root, int sum, vector<vector<int>> &result, vector<int> &inter_result) {
        if (root == nullptr) {
            return;
        }

        inter_result.push_back(root->val);
        if (root->left==nullptr && root->right==nullptr && root->val==sum) {
            result.push_back(inter_result);
            inter_result.pop_back();
            return;
        }

        resultPathSum(root->left, sum-root->val, result, inter_result);
        resultPathSum(root->right, sum-root->val, result, inter_result);

        inter_result.pop_back();
    }

    vector<vector<int>> pathSum(TreeNode* root, int sum) {
        vector<vector<int>> result;
        vector<int> inter_result;
        resultPathSum(root, sum, result, inter_result);

        return result;
    }
};