From d2e9927e97519621ba04f1e3d82684ed3cfafc5f Mon Sep 17 00:00:00 2001 From: ZongqinWang <1722249371@qq.com> Date: Fri, 3 Jun 2022 09:46:09 +0800 Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200039.=E7=BB=84=E5=90=88?= =?UTF-8?q?=E6=80=BB=E5=92=8C.md=20Scala=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0039.组合总和.md | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/problems/0039.组合总和.md b/problems/0039.组合总和.md index e10a827f..ca6312f5 100644 --- a/problems/0039.组合总和.md +++ b/problems/0039.组合总和.md @@ -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 + } +} +``` + + -----------------------