0572-subtree-of-another-tree.go

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func isSubtree(root *TreeNode, subRoot *TreeNode) bool {
	if root == nil {
		return false
	}

	return equals(root, subRoot) || isSubtree(root.Left, subRoot) || isSubtree(root.Right, subRoot)
}

func equals(s *TreeNode, t *TreeNode) bool {
	if s == nil && t == nil {
		return true
	}

	if s == nil || t == nil || s.Val != t.Val {
		return false
	}

	return equals(s.Left, t.Left) && equals(s.Right, t.Right)
}