题目描述：将一个字符串转换成一个整数，要求不能使用字符串转换整数的库函数。
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| import Foundation
class For49Solution {
func myAtoi(_ str: String) -> Int {
guard str.count > 0 else {
return 0
}
let arr = Array(str)
var begin = 0
let count = str.count - 1
var sign = 1
if arr[0] == "-" {
begin += 1
sign = -1
}else if arr[0] == "+" {
begin += 1
}else if arr[0] < "0" || arr[0] > "9" {
return 0
}
if begin > count {
return 0
}
var sum = 0
for i in begin...count {
if arr[i] < "0" || arr[i] > "9" {
return 0
}
if sign == 1 && (Int.max - Int(String(arr[i]))!*sign)/10 < sum {
return 0
}
if sign == -1 && (Int.min - Int(String(arr[i]))!*sign)/10 > sum {
return 0
}
sum = sum * 10 + Int(String(arr[i]))!*sign
}
return sum
}
}
|
github地址：https://github.com/cubegao/LeetCode
