二叉树A，B，判断B是不是A的子结构

public static boolean check(TreeNode h, TreeNode t2) {
		if (t2 == null) {
			return true;
		}
		if (h == null || h.val != t2.val) {
			return false;
		}
		return check(h.left, t2.left) && check(h.right, t2.right);
	}

	public static boolean HasSubtree(TreeNode t1, TreeNode t2) {
 		if (t2 == null) {
			return false;
		}
		if (t1 == null) {
			return false;
		}
		return check(t1, t2) || HasSubtree(t1.left, t2) || HasSubtree(t1.right, t2);
	}

     public static boolean VerifySquenceOfBST(int [] sequence) {
        if (sequence == null || sequence.length < 1) return false;
        return helper(sequence, 0, sequence.length - 1);
    }
    public static boolean helper(int [] arr, int left, int right){
        if (left == right) return true;
        int root = arr[right];
        int i;
        for(i = left; i < right; i++){
            if (arr[i] > root){
                break;
            }
        }
        int j = i;
        for(; j < right; j++){
            if (arr[j] < root){
                return false;
            }
        }
        boolean l = true;
        if (i > left){
            l = helper(arr, left,i - 1);
        }

        boolean r = true;
        if (i < right){
            r = helper(arr, i, j -1);
        }
        return  l && r;
    }