Update 0513.找树左下角的值.md

添加 0513.找树左下角的值 Java版本

problems/0513.找树左下角的值.md

@@ -217,7 +217,31 @@ public:
 
 
 Java：
-
+```java
+class Solution {
+    public int findBottomLeftValue(TreeNode root) {
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.offer(root);
+        int res = 0;
+        while (!queue.isEmpty()) {
+            int size = queue.size();
+            for (int i = 0; i < size; i++) {
+                TreeNode poll = queue.poll();
+                if (i == 0) {
+                    res = poll.val;
+                }
+                if (poll.left != null) {
+                    queue.offer(poll.left);
+                }
+                if (poll.right != null) {
+                    queue.offer(poll.right);
+                }
+            }
+        }
+        return res;
+    }
+}
+```
 
 Python：