题目描述
Given a column title as appear in an Excel sheet, return its corresponding column number.
For example:
A -> 1
B -> 2
C -> 3
...
Z -> 26
AA -> 27
AB -> 28
...
Example 1:
Input: "A"
Output: 1
Example 2:
Input: "AB"
Output: 28
Example 3:
Input: "ZY"
Output: 701
Constraints:
1 <= s.length <= 7 s consists only of uppercase English letters.
s is between "A" and "FXSHRXW".
解题思路
与168题相反, 这个是26进制转十进制, 按照正常的方法来做就好
示例代码
func titleToNumber(_ s: String) -> Int {
let cArr = Array(s)
let A: Character = "A"
var result = 0
for idx in 0..<cArr.count {
let c = cArr[idx]
if let nI = c.asciiValue,
let nA = A.asciiValue {
let offset = nI - nA + 1
result += (Int(offset) * Int(pow(26, Double(cArr.count - idx - 1))))
}
}
return result
}
