add 113

Author: awesomelike

easy/113-path-sum-2.java

@@ -0,0 +1,40 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+  public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
+    List<List<Integer>> answer = new ArrayList<>();
+    
+    solve(root, targetSum, new ArrayList<Integer>(), answer);
+    
+    return answer;
+  }
+  
+  void solve(TreeNode root, int sum, List<Integer> cur, List<List<Integer>> answer) {
+    if (root == null) {
+      return;
+    }
+    
+    cur.add(root.val);
+    if (root.val == sum && root.left == null && root.right == null) {
+      answer.add(new ArrayList<>(cur));
+    } else {
+      solve(root.left, sum - root.val, cur, answer);
+      solve(root.right, sum - root.val, cur, answer);  
+    }
+    
+    cur.remove(cur.size() - 1);
+  }
+}