From ccfb805417aa1f55efd1b30be662db8a92b46893 Mon Sep 17 00:00:00 2001
From: ZongqinWang <1722249371@qq.com>
Date: Sun, 5 Jun 2022 13:50:27 +0800
Subject: [PATCH 1/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200078.=E5=AD=90?=
=?UTF-8?q?=E9=9B=86.md=20Scala=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
problems/0078.子集.md | 54 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/problems/0078.子集.md b/problems/0078.子集.md
index e1c52b5b..3fc396a2 100644
--- a/problems/0078.子集.md
+++ b/problems/0078.子集.md
@@ -373,6 +373,60 @@ func subsets(_ nums: [Int]) -> [[Int]] {
}
```
+## Scala
+
+思路一: 使用本题解思路
+
+```scala
+object Solution {
+ import scala.collection.mutable
+ def subsets(nums: Array[Int]): List[List[Int]] = {
+ var result = mutable.ListBuffer[List[Int]]()
+ var path = mutable.ListBuffer[Int]()
+
+ def backtracking(startIndex: Int): Unit = {
+ result.append(path.toList) // 存放结果
+ if (startIndex >= nums.size) {
+ return
+ }
+ for (i <- startIndex until nums.size) {
+ path.append(nums(i)) // 添加元素
+ backtracking(i + 1)
+ path.remove(path.size - 1) // 删除
+ }
+ }
+
+ backtracking(0)
+ result.toList
+ }
+}
+```
+
+思路二: 将原问题转换为二叉树，针对每一个元素都有**选或不选**两种选择，直到遍历到最后，所有的叶子节点即为本题的答案：
+
+```scala
+object Solution {
+ import scala.collection.mutable
+ def subsets(nums: Array[Int]): List[List[Int]] = {
+ var result = mutable.ListBuffer[List[Int]]()
+
+ def backtracking(path: mutable.ListBuffer[Int], startIndex: Int): Unit = {
+ if (startIndex == nums.length) {
+ result.append(path.toList)
+ return
+ }
+ path.append(nums(startIndex))
+ backtracking(path, startIndex + 1) // 选择元素
+ path.remove(path.size - 1)
+ backtracking(path, startIndex + 1) // 不选择元素
+ }
+
+ backtracking(mutable.ListBuffer[Int](), 0)
+ result.toList
+ }
+}
+```
+
-----------------------
From b3530189489235f1212b89bd9dba0281154f366c Mon Sep 17 00:00:00 2001
From: ZongqinWang <1722249371@qq.com>
Date: Sun, 5 Jun 2022 14:13:41 +0800
Subject: [PATCH 2/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200090.=E5=AD=90?=
=?UTF-8?q?=E9=9B=86II.md=20Scala=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
problems/0090.子集II.md | 57 +++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/problems/0090.子集II.md b/problems/0090.子集II.md
index 74ce000b..9047a809 100644
--- a/problems/0090.子集II.md
+++ b/problems/0090.子集II.md
@@ -434,6 +434,63 @@ func subsetsWithDup(_ nums: [Int]) -> [[Int]] {
}
```
+### Scala
+
+不使用userd数组:
+
+```scala
+object Solution {
+ import scala.collection.mutable
+ def subsetsWithDup(nums: Array[Int]): List[List[Int]] = {
+ var result = mutable.ListBuffer[List[Int]]()
+ var path = mutable.ListBuffer[Int]()
+ var num = nums.sorted // 排序
+
+ def backtracking(startIndex: Int): Unit = {
+ result.append(path.toList)
+ if (startIndex >= num.size){
+ return
+ }
+ for (i <- startIndex until num.size) {
+ // 同一树层重复的元素不进入回溯
+ if (!(i > startIndex && num(i) == num(i - 1))) {
+ path.append(num(i))
+ backtracking(i + 1)
+ path.remove(path.size - 1)
+ }
+ }
+ }
+
+ backtracking(0)
+ result.toList
+ }
+}
+```
+
+使用Set去重:
+```scala
+object Solution {
+ import scala.collection.mutable
+ def subsetsWithDup(nums: Array[Int]): List[List[Int]] = {
+ var result = mutable.Set[List[Int]]()
+ var num = nums.sorted
+ def backtracking(path: mutable.ListBuffer[Int], startIndex: Int): Unit = {
+ if (startIndex == num.length) {
+ result.add(path.toList)
+ return
+ }
+ path.append(num(startIndex))
+ backtracking(path, startIndex + 1) // 选择
+ path.remove(path.size - 1)
+ backtracking(path, startIndex + 1) // 不选择
+ }
+
+ backtracking(mutable.ListBuffer[Int](), 0)
+
+ result.toList
+ }
+}
+```
-----------------------
From 068cc095353ceb240c98a6c2b8598e98c445260b Mon Sep 17 00:00:00 2001
From: ZongqinWang <1722249371@qq.com>
Date: Sun, 5 Jun 2022 14:46:21 +0800
Subject: [PATCH 3/3] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200491.=E9=80=92?=
=?UTF-8?q?=E5=A2=9E=E5=AD=90=E5=BA=8F=E5=88=97.md=20Scala=E7=89=88?=
=?UTF-8?q?=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
---
problems/0491.递增子序列.md | 34 ++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/problems/0491.递增子序列.md b/problems/0491.递增子序列.md
index 3ea2382b..a04d433b 100644
--- a/problems/0491.递增子序列.md
+++ b/problems/0491.递增子序列.md
@@ -522,5 +522,39 @@ func findSubsequences(_ nums: [Int]) -> [[Int]] {
```
+## Scala
+
+```scala
+object Solution {
+ import scala.collection.mutable
+ def findSubsequences(nums: Array[Int]): List[List[Int]] = {
+ var result = mutable.ListBuffer[List[Int]]()
+ var path = mutable.ListBuffer[Int]()
+
+ def backtracking(startIndex: Int): Unit = {
+ // 集合元素大于1，添加到结果集
+ if (path.size > 1) {
+ result.append(path.toList)
+ }
+
+ var used = new Array[Boolean](201)
+ // 使用循环守卫，当前层没有用过的元素才有资格进入回溯
+ for (i <- startIndex until nums.size if !used(nums(i) + 100)) {
+ // 如果path没元素或 当前循环的元素比path的最后一个元素大，则可以进入回溯
+ if (path.size == 0 || (!path.isEmpty && nums(i) >= path(path.size - 1))) {
+ used(nums(i) + 100) = true
+ path.append(nums(i))
+ backtracking(i + 1)
+ path.remove(path.size - 1)
+ }
+ }
+ }
+
+ backtracking(0)
+ result.toList
+ }
+}
+```
+
-----------------------
