Given a string s formed by digits ('0' - '9') and '#' . We want to map s to English lowercase characters as follows:
Characters ('a' to 'i') are represented by ('1' to '9') respectively.
Characters ('j' to 'z') are represented by ('10#' to '26#') respectively.
Return the string formed after mapping.
It's guaranteed that a unique mapping will always exist.
Example 1:
Input: s = "10#11#12"
Output: "jkab"
Explanation: "j" -> "10#" , "k" -> "11#" , "a" -> "1" , "b" -> "2".Example 2:
Input: s = "1326#"
Output: "acz"Example 3:
Input: s = "25#"
Output: "y"Example 4:
Input: s = "12345678910#11#12#13#14#15#16#17#18#19#20#21#22#23#24#25#26#"
Output: "abcdefghijklmnopqrstuvwxyz"Constraints:
1 <= s.length <= 1000
s[i] only contains digits letters ('0'-'9') and '#' letter.
s will be valid string such that mapping is always possible.Solution:
using System;
using System.Collections.Generic;
using System.Text;
namespace LeetCode.AskGif.Easy.String
{
class FreqAlphabetsSol
{
public void execute()
{
var res = FreqAlphabets("10#11#12");
}
public string FreqAlphabets(string s)
{
string[] alphabet = {"","a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p",
"q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
var str = new StringBuilder();
for (int i = 0; i < s.Length; i++)
{
if(i+2 < s.Length && s[i+2] == '#')
{
str.Append(alphabet[Int32.Parse(s.Substring(i, 2))]);
i += 2;
}
else
{
str.Append(alphabet[Int32.Parse(s.Substring(i, 1))]);
}
}
return str.ToString();
}
}
}
Time Complexity: O(n) - for traversing the string
Space Complexity: O(1)
