add: leetcode 1609 solution

leetcode/1609.Even-Odd-Tree/1609.Even Odd Tree.go

@@ -0,0 +1,72 @@
+package leetcode
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func isEvenOddTree(root *TreeNode) bool {
+	level := 0
+	queue := []*TreeNode{root}
+	for len(queue) != 0 {
+		length := len(queue)
+		var nums []int
+		for i := 0; i < length; i++ {
+			node := queue[i]
+			if node.Left != nil {
+				queue = append(queue, node.Left)
+			}
+			if node.Right != nil {
+				queue = append(queue, node.Right)
+			}
+			nums = append(nums, node.Val)
+		}
+		if level%2 == 0 {
+			if !even(nums) {
+				return false
+			}
+		} else {
+			if !odd(nums) {
+				return false
+			}
+		}
+		queue = queue[length:]
+		level++
+	}
+	return true
+}
+
+func odd(nums []int) bool {
+	cur := nums[0]
+	if cur%2 != 0 {
+		return false
+	}
+	for _, num := range nums[1:] {
+		if num >= cur {
+			return false
+		}
+		if num%2 != 0 {
+			return false
+		}
+		cur = num
+	}
+	return true
+}
+
+func even(nums []int) bool {
+	cur := nums[0]
+	if cur%2 == 0 {
+		return false
+	}
+	for _, num := range nums[1:] {
+		if num <= cur {
+			return false
+		}
+		if num%2 == 0 {
+			return false
+		}
+		cur = num
+	}
+	return true
+}