Merge pull request #1431 from wzqwtt/backtracking03

添加(0039.组合总和、0040.组合总和II) Scala版本
This commit is contained in:
程序员Carl
2022-07-07 09:02:49 +08:00
committed by GitHub
2 changed files with 62 additions and 0 deletions

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@ -502,5 +502,35 @@ func combinationSum(_ candidates: [Int], _ target: Int) -> [[Int]] {
}
```
## Scala
```scala
object Solution {
import scala.collection.mutable
def combinationSum(candidates: Array[Int], target: Int): List[List[Int]] = {
var result = mutable.ListBuffer[List[Int]]()
var path = mutable.ListBuffer[Int]()
def backtracking(sum: Int, index: Int): Unit = {
if (sum == target) {
result.append(path.toList) // 如果正好等于target就添加到结果集
return
}
// 应该是从当前索引开始的而不是从0
// 剪枝优化添加循环守卫当sum + c(i) <= target的时候才循环才可以进入下一次递归
for (i <- index until candidates.size if sum + candidates(i) <= target) {
path.append(candidates(i))
backtracking(sum + candidates(i), i)
path = path.take(path.size - 1)
}
}
backtracking(0, 0)
result.toList
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

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@ -693,5 +693,37 @@ func combinationSum2(_ candidates: [Int], _ target: Int) -> [[Int]] {
}
```
## Scala
```scala
object Solution {
import scala.collection.mutable
def combinationSum2(candidates: Array[Int], target: Int): List[List[Int]] = {
var res = mutable.ListBuffer[List[Int]]()
var path = mutable.ListBuffer[Int]()
var candidate = candidates.sorted
def backtracking(sum: Int, startIndex: Int): Unit = {
if (sum == target) {
res.append(path.toList)
return
}
for (i <- startIndex until candidate.size if sum + candidate(i) <= target) {
if (!(i > startIndex && candidate(i) == candidate(i - 1))) {
path.append(candidate(i))
backtracking(sum + candidate(i), i + 1)
path = path.take(path.size - 1)
}
}
}
backtracking(0, 0)
res.toList
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>