515.在每个树行中找最大值.go

/*
 * @lc app=leetcode.cn id=515 lang=golang
 *
 * [515] 在每个树行中找最大值
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */

/**
 * BFS
 */
func largestValues(root *TreeNode) []int {
	ans := []int{}
	if root == nil {
		return ans
	}
	q := []*TreeNode{root}
	for len(q) > 0 {
		size := len(q)
		maxVal := q[0].Val
		for i := 0; i < size; i++ {
			node := q[i]
			if node.Val > maxVal {
				maxVal = node.Val
			}
			if node.Left != nil {
				q = append(q, node.Left)
			}
			if node.Right != nil {
				q = append(q, node.Right)
			}
		}
		ans = append(ans, maxVal)
		q = q[size:]
	}
	return ans
}

// @lc code=end