// Package q1022 implements a solution for https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/
package q1022

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func sum(node *TreeNode, prefix int, ret *int) {
	if node == nil {
		return
	}
	num := prefix<<1 + node.Val

	if node.Left == nil && node.Right == nil {
		*ret += num
	} else {
		sum(node.Left, num, ret)
		sum(node.Right, num, ret)
	}
}

func sumRootToLeaf(root *TreeNode) int {
	ret := 0
	sum(root, 0, &ret)
	return ret
}

var _ = sumRootToLeaf