package binary_tree

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

const null = -65535

// BuildTree 给定 [3,4,8,9,null, null,10]构造一个二叉树，应该像下面的样子
//					  3
//				4			8
//			9					10
// queue[i].left = node[2*i+1]
// queue[i].right = node[2*i+2]
func BuildTree(values []int) *TreeNode {
	if len(values) == 0 {
		return nil
	}
	queue := make([]*TreeNode, 0, len(values))
	for _, value := range values {
		if value != null {
			queue = append(queue, &TreeNode{value, nil, nil})
		} else {
			queue = append(queue, nil)
		}
	}
	for i, node := range queue {
		if node != nil && 2*i+1 < len(queue) && queue[2*i+1] != nil {
			node.Left = queue[2*i+1]
		}
		if node != nil && 2*i+2 < len(queue) && queue[2*i+2] != nil {
			node.Right = queue[2*i+2]
		}
	}
	return queue[0]
}