树的子结构

题目：

输入两棵二叉树A和B，判断B是不是A的子结构。

解答：

public class Solution {

    public static boolean HashSubTree(TreeNode root1, TreeNode root2) {
        boolean result = false;

        if(root1 != null && root2 != null) {
            if(Equal(root1.val, root2.val)) {
                result = DoesTree1HaveTree2(root1, root2);
            }

            if(!result) {
                result = DoesTree1HaveTree2(root1.left, root2);
            }

            if(!result) {
                result = DoesTree1HaveTree2(root1.right, root2);
            }
        }

        return result;
    }

    private static boolean Equal(int val1, int val2) {
        return val1 == val2? true:false;
    }

    private static boolean DoesTree1HaveTree2(TreeNode root1, TreeNode root2) {
        if(root2 == null) {
            return true;
        }

        if(root1 == null) {
            return false;
        }

        if(!Equal(root1.val, root2.val)) {
            return false;
        }

        return DoesTree1HaveTree2(root1.left, root2.left) && DoesTree1HaveTree2(root1.right, root2.right);
    }
}