feat:add Solution.cpp for 0113. Path Sum II

Author: Stackingrule

solution/0100-0199/0113.Path Sum II/Solution.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    vector<vector<int>> pathSum(TreeNode* root, int sum) {
+        vector<vector<int>> res;
+        vector<int> out;
+        helper(root, sum, out, res);
+        return res;
+    }
+
+private:
+    void helper(TreeNode *node, int sum, vector<int> &out, vector<vector<int>> &res) {
+        if (!node) return;
+        out.push_back(node->val);
+        if (sum == node->val && !node->left && !node->right) {
+            res.push_back(out);
+        }
+        helper(node->left, sum - node->val, out, res);
+        helper(node->right, sum - node->val, out, res);
+        out.pop_back();
+    }
+};