Longest Univalue Path.go

func max(v0 int, v1 int) int {
	if v0 < v1 {
		return v1
	}
	return v0
}

func longestUnivaluePathInternal(root *TreeNode, value int) int {
	if nil == root || root.Val != value{
		return 0
	}
	leftMax := longestUnivaluePathInternal(root.Left, value)
	rightMax := longestUnivaluePathInternal(root.Right, value)
	return max(leftMax, rightMax) + 1
}

func longestUnivaluePath(root *TreeNode) int {
	if nil == root {
		return 0
	}
	var result = longestUnivaluePathInternal(root.Left, root.Val) + longestUnivaluePathInternal(root.Right, root.Val)
	result = max(result, longestUnivaluePath(root.Left))
	return  max(result, longestUnivaluePath(root.Right))
}