The Swift Programming Language Book Chapter Section 控制流实验 3答案

【问题标题】：The Swift Programming Language Book Chapter Section on Control Flow Experiment 3The Swift Programming Language Book Chapter Section 控制流实验 3
【发布时间】：2014-06-03 22:02:28
【问题描述】：

我正在阅读本书的第一章，但无法弄清楚实验：

添加另一个变量来跟踪哪个数字是最大的，以及最大的数字是多少。

这是书中的代码：

let interstingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13, 17],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25, 36],
]
var largest = 0
for (kind, numbers) in interstingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
        }
    }
}
largest

【问题讨论】：

标签： ios swift

【解决方案1】：

像这样：

let interstingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13, 17],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25, 36],
]
var largest = 0
var largestKind = ""
for (kind, numbers) in interstingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            largestKind = kind
        }
    }
}
largest
largestKind

【讨论】：

非常感谢 :)
@user3704869 您还可以考虑使用元组将最大数字和种类存储在一种复合类型中。试试看吧。
非常感谢您的提示

【解决方案2】：

所以基本上你想在将number 放入largest 的同时将kind 放入某个地方，例如到一个名为largestKind的变量中。

【讨论】：

【解决方案3】：

要求跟踪值和类型的问题不仅仅是显示最终答案的类型。我认为这更接近：

let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25],
]

var largest = 0
var largestType = [String]()
var largestValues = [Int]()
for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            largestValues.append(largest)
            largestType.append(kind)
        }
    }
}

print(largest)
print(largestType)
print(largestValues)

现在有了元组：

let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25],
]

var largest = 0
var largestValues: [(type: String, value: Int)] = []
for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            largestValues.append(type: kind, value: number)
        }
    }
}

print(largest)
print(largestValues)

【讨论】：

元组变体是最干净的恕我直言。感谢这个例子！

【解决方案4】：

let interestingNumbers = [ "Prime"     : [2,3,5,7,11,13],
                           "Fibonacci" : [1,1,2,3,5,8,13],
                           "Square"    : [1,4,9,16,25,36],
                         ]

var largest = 0
var largestKind = ""

for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            largestKind = kind
        }
    } 
}

print(largest, largestKind)

outputs : 36 Sqaure

【讨论】：

【解决方案5】：

let interestingNumbers = [
      "Prime": [2, 3, 5, 7, 11, 13],
      "Fibonacci": [1, 1, 2, 3, 5, 8],
      "Square": [1, 4, 9, 16, 25],
]

 var largest = 0
 var largestNumbers = [
     "Prime":0,
     "Fibonacci":0,
     "Square":0,
]


for (kind, numbers) in interestingNumbers {

  for number in numbers {

    if number > largest {
        largest = number
    }

    if(number > largestNumbers[kind]!){
        largestNumbers[kind] = number;
    }
}
}

print(largest)
print(largestNumbers)


Result is:
25
["Fibonacci": 8, "Square": 25, "Prime": 13]

【讨论】：