动态规划

判断一棵树是否是另一棵树的子树

参考了第一个解答

/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public boolean HasSubtree(TreeNode root1,TreeNode root2) {
         if(root1==null || root2==null) return false;
       boolean flag = false;
        if(root1.val == root2.val)
        {
            flag = isSubTree(root1,root2);
        }
        if(!flag)
        {
            flag = HasSubtree(root1.left,root2);
            if(! flag)
            {
                flag = HasSubtree(root1.right,root2);
            }
        }
        return flag;
    }
    public boolean isSubTree(TreeNode root1, TreeNode root2){
        if(root1 == null && root2 != null)
            return false;
        if (root2 == null)
            return true;
        if (root1.val == root2.val)
        {
            return isSubTree(root1.left, root2.left)&&isSubTree(root1.right, root2.right);
        }
        else
            return false;
    }
}