Commit e56e94d

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tumanob

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Update solution scala for "20 Valid Parentheses"

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ScalaSolutions/src/main/scala/ValidParentheses_p20
- Solution.scala

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`‎ScalaSolutions/src/main/scala/ValidParentheses_p20/Solution.scala`

Lines changed: 11 additions & 55 deletions

Original file line number	Diff line number	Diff line change
`@@ -14,9 +14,6 @@ import scala.collection.mutable.Stack`
`14`	`14`	`*/`
`15`	`15`	`object Solution {`
`16`	`16`
`17`		`- val OpenToClose: Map[Char, Char] = Map('{' -> '}', '[' -> ']', '(' -> ')')`
`18`		`- val CloseToOpen: Map[Char, Char] = OpenToClose.map(_.swap)`
`19`		`-`
`20`	`17`	`def main(args: Array[String]): Unit = {`
`21`	`18`	`println(!isValid("["))`
`22`	`19`	`println(isValid("()[]{}")) // all should be true`
`@@ -31,63 +28,22 @@ object Solution {`
`31`	`28`	`}`
`32`	`29`
`33`	`30`	`def isValid(s: String): Boolean = {`
`34`		`- stackParenthesisSolution(s) // Stack Solution`
`35`		`- //parenthesesAreBalanced(s) // Tail recursion solution`
`36`		`- }`
`37`		`-`
`38`		`- import scala.collection.mutable.Stack`
`39`		`- /**`
`40`		`- * Stack solution`
`41`		`- */`
`42`		`- def stackParenthesisSolution(s: String): Boolean = {`
	`31`	`+ import scala.collection.mutable.Stack`
`43`	`32`	`val stack = new Stack[Char]()`
`44`		`- if (s.size ==0) stack.push('f')`
`45`		`-`
`46`		`- s.foreach(char=> {`
	`33`	`+ valOpenToClose:Map[Char, Char] =Map('{'->'}', '['->']', '('->')')`
	`34`	`+`
	`35`	`+ defcheckPar(char: Char):Boolean= {`
`47`	`36`	`if (OpenToClose.contains(char)) {`
`48`	`37`	`stack.push(char)`
	`38`	`+ true`
	`39`	`+ } else if (stack.size > 0 && OpenToClose.get(stack.top) == Some(char)) {`
	`40`	`+ stack.pop()`
	`41`	`+ true`
`49`	`42`	`} else {`
`50`		`- if (stack.size > 0 && OpenToClose.get(stack.top) == Some(char))`
`51`		`- stack.pop()`
`52`		`- else`
`53`		`- stack.push('f')`
`54`		`- }`
`55`		`- })`
`56`		`-`
`57`		`- stack.size == 0`
`58`		`- }`
`59`		`-`
`60`		`- /**`
`61`		`- * Tail recursion solution`
`62`		`- * is taken from https://www.scala-algorithms.com/ParenthesesTailRecursive/`
`63`		`- *`
`64`		`- * @param`
`65`		`- * @return`
`66`		`- */`
`67`		`- def parenthesesAreBalanced(s: String): Boolean = {`
`68`		`- if (s.isEmpty) true`
`69`		`- else {`
`70`		`- @scala.annotation.tailrec`
`71`		`- def go(position: Int, stack: List[Char]): Boolean = {`
`72`		`- if (position == s.length) stack.isEmpty`
`73`		`- else {`
`74`		`- val char = s(position)`
`75`		`- val isOpening = OpenToClose.contains(char)`
`76`		`- val isClosing = CloseToOpen.contains(char)`
`77`		`- if (isOpening) go(position + 1, char :: stack)`
`78`		`- else if (isClosing) {`
`79`		`- val expectedCharForMatching = CloseToOpen(char)`
`80`		`- stack match {`
`81`		- case `expectedCharForMatching` :: rest =>
`82`		`- go(position + 1, rest)`
`83`		`- case _ =>`
`84`		`- false`
`85`		`- }`
`86`		`- } else false`
`87`		`- }`
	`43`	`+ false`
`88`	`44`	`}`
`89`		`-`
`90`		`- go(position = 0, stack = List.empty)`
`91`	`45`	`}`
	`46`	`+`
	`47`	`+ s.size > 0 && s.forall(checkPar) && stack.size == 0`
`92`	`48`	`}`
`93`	`49`	`}`

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`‎ScalaSolutions/src/main/scala/ValidParentheses_p20/Solution.scala`

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