diff --git a/problems/0017.电话号码的字母组合.md b/problems/0017.电话号码的字母组合.md index 2b5cb978..e357a33b 100644 --- a/problems/0017.电话号码的字母组合.md +++ b/problems/0017.电话号码的字母组合.md @@ -557,6 +557,37 @@ func letterCombinations(_ digits: String) -> [String] { } ``` +## Scala: + +```scala +object Solution { + import scala.collection.mutable + def letterCombinations(digits: String): List[String] = { + var result = mutable.ListBuffer[String]() + if(digits == "") return result.toList // 如果参数为空,返回空结果集的List形式 + var path = mutable.ListBuffer[Char]() + // 数字和字符的映射关系 + val map = Array[String]("", "", "abc", "def", "ghi", "jkl", "mno", "pqrs", "tuv", "wxyz") + + def backtracking(index: Int): Unit = { + if (index == digits.size) { + result.append(path.mkString) // mkString语法:将数组类型直接转换为字符串 + return + } + var digit = digits(index) - '0' // 这里使用toInt会报错!必须 -'0' + for (i <- 0 until map(digit).size) { + path.append(map(digit)(i)) + backtracking(index + 1) + path = path.take(path.size - 1) + } + } + + backtracking(0) + result.toList + } +} +``` + -----------------------
diff --git a/problems/0216.组合总和III.md b/problems/0216.组合总和III.md index 0ace0fd5..2c1bf717 100644 --- a/problems/0216.组合总和III.md +++ b/problems/0216.组合总和III.md @@ -502,5 +502,35 @@ func combinationSum3(_ count: Int, _ targetSum: Int) -> [[Int]] { } ``` +## Scala + +```scala +object Solution { + import scala.collection.mutable + def combinationSum3(k: Int, n: Int): List[List[Int]] = { + var result = mutable.ListBuffer[List[Int]]() + var path = mutable.ListBuffer[Int]() + + def backtracking(k: Int, n: Int, sum: Int, startIndex: Int): Unit = { + if (sum > n) return // 剪枝,如果sum>目标和,就返回 + if (sum == n && path.size == k) { + result.append(path.toList) + return + } + // 剪枝 + for (i <- startIndex to (9 - (k - path.size) + 1)) { + path.append(i) + backtracking(k, n, sum + i, i + 1) + path = path.take(path.size - 1) + } + } + + backtracking(k, n, 0, 1) // 调用递归方法 + result.toList // 最终返回结果集的List形式 + } +} +``` + + -----------------------