SymmetricTree.java

src/SymmetricTree.java

@@ -0,0 +1,35 @@
+package Tree;
+
+import ListNode.TreeNode;
+
+/**
+ * 
+ * @author chenqun
+ * Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
+ *
+ */
+public class SymmetricTree {
+
+	public boolean isSymmetric(TreeNode root){
+		if(root == null)
+			return true;
+		else 
+			return isSymmetricTwoTree(root.left, root.right);
+	}
+	//判断两棵树是不是对称的
+	public boolean isSymmetricTwoTree(TreeNode t1, TreeNode t2){
+		if(t1 == null && t2 == null)
+			return true;
+		if(t1 == null || t2 == null)
+			return false;
+		if(t1.val != t2.val){
+			return false;
+		}
+		return isSymmetricTwoTree(t1.left,t2.right) && isSymmetricTwoTree(t1.right , t2.left);
+	}
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}