Question

我有以下代码用于读取2个整数：

Array(N, Q) = readLine.split(" ").map(_.toInt)

为此，我收到以下错误：

error: value update is not a member of object Array

如果我这样做

val Array(N, Q) = readLine.split(" ").map(_.toInt)

我明白了：

error: not found: value N

如果我之前申报：

val N, Q

我明白了：

!error: '=' expected but ';' found.

那么如何同时读取这些整数呢？

Answer 1

不要将变量名称大写。

let myString = "aaabbb"
var myOutput: Int?
let numChars = myString.characters.count

if numChars%2 == 0 {

    let midIndex = myString.startIndex.advancedBy(numChars/2)
    let myLeftString = myString.substringToIndex(midIndex)
    let myRightString = myString.substringFromIndex(midIndex)

    let numDifferentLetters = 26 // asymptotic behaviour: assume n > numDifferentLetters
    var letterOccurencesLhs = [Int](count: numDifferentLetters, repeatedValue: 0) // < n
    var letterOccurencesRhs = letterOccurencesLhs // swift: arr value type, < n

    // n/2
    for charAscii in myLeftString.utf8 {
        letterOccurencesLhs[Int(charAscii)-96] += 1
    }

    // n/2
    for charAscii in myRightString.utf8 {
        letterOccurencesRhs[Int(charAscii)-96] += 1
    }

    // check order of compliance for each letter, w.r.t. numDiffLetters, < n
    var mySum = 0
    for i in 0 ..< numDifferentLetters {
        if letterOccurencesLhs[i] * letterOccurencesRhs[i] > 0 {
            mySum += min(letterOccurencesLhs[i], letterOccurencesRhs[i])
        }
    }

    myOutput = numChars/2-mySum

}
else {
    myOutput = -1
}

print("Output: \(myOutput!)") // 3 for "aaabbb"
                              // 2 for "aaabbbbbbbab"

    // Complexity: O(n)

Scala模式匹配以大写字母开头的特殊情况标识符。

Scala同时读取两个整数错误

1 个答案: