Create 湛江甲鸟.md

zjduck0728 · web-flow · commit e14b2c3a99c3 · 2018-12-05T22:11:44.000+08:00
diff --git a/2018.12.04-leetcode101/湛江甲鸟.md b/2018.12.04-leetcode101/湛江甲鸟.md
@@ -0,0 +1,45 @@
+#### 递归
+```
+public boolean isSymmetric(TreeNode root) {
+    if (root == null)
+        return true;
+    return dfs(root.left, root.right);
+}
+
+private boolean dfs(TreeNode node1, TreeNode node2) {
+    if ((node1 == null && node2 == null)) {
+        return true;
+    } else if (node1 != null && node2 != null) {
+        if (node1.val != node2.val) {
+            return false;
+        }   
+    } else {
+        return false;
+    }    
+    return dfs(node1.left, node2.right) && dfs(node1.right, node2.left);
+}
+```
+
+#### 非递归
+```
+public boolean isSymmetric(TreeNode root) {
+    Queue<TreeNode> q = new LinkedList<>();
+    q.add(root);
+    q.add(root);
+    while (!q.isEmpty()) {
+        TreeNode t1 = q.poll();
+        TreeNode t2 = q.poll();
+        if (t1 == null && t2 == null) {
+            continue;
+        }
+        if (t1 == null || t2 == null || t1.val != t2.val) {
+            return false;
+        }
+        q.add(t1.left);
+        q.add(t2.right);
+        q.add(t1.right);
+        q.add(t2.left);
+    }
+    return true;
+}
+```
