Merge pull request #219 from gostool/leetcode1609

Leetcode1609

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
+}

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

@@ -0,0 +1,73 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1609 struct {
+	para1609
+	ans1609
+}
+
+// para 是参数
+type para1609 struct {
+	root *TreeNode
+}
+
+// ans 是答案
+type ans1609 struct {
+	ans bool
+}
+
+func Test_Problem1609(t *testing.T) {
+
+	qs := []question1609{
+
+		{
+			para1609{&TreeNode{1,
+				&TreeNode{10,
+					&TreeNode{3, &TreeNode{12, nil, nil}, &TreeNode{8, nil, nil}}, nil},
+				&TreeNode{4, &TreeNode{7, &TreeNode{6, nil, nil}, nil}, &TreeNode{9, nil, &TreeNode{2, nil, nil}}}}},
+			ans1609{true},
+		},
+
+		{
+			para1609{&TreeNode{5,
+				&TreeNode{4, &TreeNode{3, nil, nil}, &TreeNode{3, nil, nil}},
+				&TreeNode{2, &TreeNode{7, nil, nil}, nil}}},
+			ans1609{false},
+		},
+
+		{
+			para1609{&TreeNode{5,
+				&TreeNode{9, &TreeNode{3, nil, nil}, &TreeNode{5, nil, nil}},
+				&TreeNode{1, &TreeNode{7, nil, nil}, nil}}},
+			ans1609{false},
+		},
+
+		{
+			para1609{&TreeNode{1, nil, nil}},
+			ans1609{true},
+		},
+
+		{
+			para1609{&TreeNode{11,
+				&TreeNode{8,
+					&TreeNode{1, &TreeNode{30, &TreeNode{17, nil, nil}, nil}, &TreeNode{20, nil, nil}},
+					&TreeNode{3, &TreeNode{18, nil, nil}, &TreeNode{16, nil, nil}}},
+				&TreeNode{6,
+					&TreeNode{9, &TreeNode{12, nil, nil}, &TreeNode{10, nil, nil}},
+					&TreeNode{11, &TreeNode{4, nil, nil}, &TreeNode{2, nil, nil}}}}},
+			ans1609{true},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1609------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1609, q.para1609
+		fmt.Printf("【input】:%v    【output】:%v\n", p.root, isEvenOddTree(p.root))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/1609.Even-Odd-Tree/README.md

@@ -0,0 +1,150 @@
+# [1609. Even Odd Tree](https://leetcode-cn.com/problems/even-odd-tree/)
+
+## 题目
+
+A binary tree is named Even-Odd if it meets the following conditions:
+
+- The root of the binary tree is at level index 0, its children are at level index 1, their children are at level index 2, etc.
+- For every even-indexed level, all nodes at the level have odd integer values in strictly increasing order (from left to right).
+- For every odd-indexed level, all nodes at the level have even integer values in strictly decreasing order (from left to right).
+
+Given the root of a binary tree, return true if the binary tree is Even-Odd, otherwise return false.
+
+**Example 1**:
+
+![https://assets.leetcode.com/uploads/2020/09/15/sample_1_1966.png](https://assets.leetcode.com/uploads/2020/09/15/sample_1_1966.png)
+
+    Input: root = [1,10,4,3,null,7,9,12,8,6,null,null,2]
+    Output: true
+    Explanation: The node values on each level are:
+    Level 0: [1]
+    Level 1: [10,4]
+    Level 2: [3,7,9]
+    Level 3: [12,8,6,2]
+    Since levels 0 and 2 are all odd and increasing and levels 1 and 3 are all even and decreasing, the tree is Even-Odd.
+
+**Example 2**:
+
+![https://assets.leetcode.com/uploads/2020/09/15/sample_2_1966.png](https://assets.leetcode.com/uploads/2020/09/15/sample_2_1966.png)
+
+    Input: root = [5,4,2,3,3,7]
+    Output: false
+    Explanation: The node values on each level are:
+    Level 0: [5]
+    Level 1: [4,2]
+    Level 2: [3,3,7]
+    Node values in level 2 must be in strictly increasing order, so the tree is not Even-Odd.
+
+**Example 3**:
+
+![https://assets.leetcode.com/uploads/2020/09/22/sample_1_333_1966.png](https://assets.leetcode.com/uploads/2020/09/22/sample_1_333_1966.png)
+
+    Input: root = [5,9,1,3,5,7]
+    Output: false
+    Explanation: Node values in the level 1 should be even integers.
+
+**Example 4**:
+
+    Input: root = [1]
+    Output: true
+
+**Example 5**:
+
+    Input: root = [11,8,6,1,3,9,11,30,20,18,16,12,10,4,2,17]
+    Output: True
+
+**Constraints:**
+
+- The number of nodes in the tree is in the range [1, 100000]. 
+- 1 <= Node.val <= 1000000
+
+## 题目大意
+
+如果一棵二叉树满足下述几个条件，则可以称为 奇偶树 ：
+
+- 二叉树根节点所在层下标为 0 ，根的子节点所在层下标为 1 ，根的孙节点所在层下标为 2 ，依此类推。
+- 偶数下标 层上的所有节点的值都是 奇 整数，从左到右按顺序 严格递增
+- 奇数下标 层上的所有节点的值都是 偶 整数，从左到右按顺序 严格递减
+
+给你二叉树的根节点，如果二叉树为 奇偶树 ，则返回 true ，否则返回 false 。
+
+## 解题思路
+
+- 广度优先遍历(分别判断奇数层和偶数层)
+
+## 代码
+
+```go
+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
+}
+```