From bbd1b2e9ca58ae177f3d656752cd01a2ee15f7a2 Mon Sep 17 00:00:00 2001 From: ironartisan Date: Fri, 3 Sep 2021 17:19:26 +0800 Subject: [PATCH 1/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A00102.=E4=BA=8C=E5=8F=89?= =?UTF-8?q?=E6=A0=91=E7=9A=84=E5=B1=82=E5=BA=8F=E9=81=8D=E5=8E=86=E9=80=92?= =?UTF-8?q?=E5=BD=92=E8=A7=A3=E6=B3=95Python=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0102.二叉树的层序遍历.md | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/problems/0102.二叉树的层序遍历.md b/problems/0102.二叉树的层序遍历.md index a57a92aa..baec1229 100644 --- a/problems/0102.二叉树的层序遍历.md +++ b/problems/0102.二叉树的层序遍历.md @@ -88,6 +88,7 @@ public: python代码： ```python +# 迭代法 class Solution: def levelOrder(self, root: TreeNode) -> List[List[int]]: if not root: @@ -108,7 +109,20 @@ class Solution: return out_list ``` - +```python +# 递归法 +class Solution: + def levelOrder(self, root: TreeNode) -> List[List[int]]: + res = [] + def helper(root, depth): + if not root: return [] + if len(res) == depth: res.append([]) # start the current depth + res[depth].append(root.val) # fulfil the current depth + if root.left: helper(root.left, depth + 1) # process child nodes for the next depth + if root.right: helper(root.right, depth + 1) + helper(root, 0) + return res +``` java: ```Java From 659b34c22f171d011ce8b9e3a826954183c30315 Mon Sep 17 00:00:00 2001 From: ironartisan Date: Sat, 4 Sep 2021 15:06:39 +0800 Subject: [PATCH 2/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A00222.=E5=AE=8C=E5=85=A8?= =?UTF-8?q?=E4=BA=8C=E5=8F=89=E6=A0=91=E7=9A=84=E8=8A=82=E7=82=B9=E4=B8=AA?= =?UTF-8?q?=E6=95=B0=E8=BF=AD=E4=BB=A3=E8=A7=A3=E6=B3=95Java=E4=BB=A3?= =?UTF-8?q?=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0222.完全二叉树的节点个数.md | 22 ++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/problems/0222.完全二叉树的节点个数.md b/problems/0222.完全二叉树的节点个数.md index 6268c447..13017f7f 100644 --- a/problems/0222.完全二叉树的节点个数.md +++ b/problems/0222.完全二叉树的节点个数.md @@ -204,7 +204,27 @@ class Solution { } } ``` - +```java +class Solution { + // 迭代法 + public int countNodes(TreeNode root) { + if (root == null) return 0; + Queue queue = new LinkedList<>(); + queue.offer(root); + int result = 0; + while (!queue.isEmpty()) { + int size = queue.size(); + while (size -- > 0) { + TreeNode cur = queue.poll(); + result++; + if (cur.left != null) queue.offer(cur.left); + if (cur.right != null) queue.offer(cur.right); + } + } + return result; + } +} +``` ```java class Solution { /** From b83cc1602a91c6d9ad3268904d17be42415d6938 Mon Sep 17 00:00:00 2001 From: ironartisan <54694467+ironartisan@users.noreply.github.com> Date: Sun, 5 Sep 2021 10:27:23 +0800 Subject: [PATCH 3/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A00404.=E5=B7=A6=E5=8F=B6?= =?UTF-8?q?=E5=AD=90=E4=B9=8B=E5=92=8C.md=E5=B1=82=E5=BA=8F=E8=BF=AD?= =?UTF-8?q?=E4=BB=A3=E8=A7=A3=E6=B3=95Java=E4=BB=A3=E7=A0=81?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0404.左叶子之和.md | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md index 2b627b6c..c0eb7c8e 100644 --- a/problems/0404.左叶子之和.md +++ b/problems/0404.左叶子之和.md @@ -201,7 +201,31 @@ class Solution { } } ``` - +```java +// 层序遍历迭代法 +class Solution { + public int sumOfLeftLeaves(TreeNode root) { + int sum = 0; + if (root == null) return 0; + Queue queue = new LinkedList<>(); + queue.offer(root); + while (!queue.isEmpty()) { + int size = queue.size(); + while (size -- > 0) { + TreeNode node = queue.poll(); + if (node.left != null) { // 左节点不为空 + queue.offer(node.left); + if (node.left.left == null && node.left.right == null){ // 左叶子节点 + sum += node.left.val; + } + } + if (node.right != null) queue.offer(node.right); + } + } + return sum; + } +} +``` ## Python