Create FFFro.md

FFFro · web-flow · commit c03fd090b3de · 2018-12-05T13:04:07.000+08:00
diff --git a/2018.12.05-leetcode102/FFFro.md b/2018.12.05-leetcode102/FFFro.md
@@ -0,0 +1,27 @@
+import java.util.ArrayList;
+import java.util.List;
+
+class Solution {
+    public List<List<Integer>> levelOrder(TreeNode root) {
+        List<List<Integer>> list = new ArrayList<>();
+        if (root == null) {
+            return list;
+        }
+        levelOrder(root,0,list);
+        return list;
+    }
+
+    private void levelOrder(TreeNode root, int i, List<List<Integer>> list) {
+        if (root == null)
+            return;
+        if (list.size() == i){
+            List<Integer> a = new ArrayList<>();
+            a.add(root.val);
+            list.add(a);
+        }else {
+            list.get(i).add(root.val);
+        }
+        levelOrder(root.left,i+1,list);
+        levelOrder(root.right,i+1,list);
+    }
+}
