program to find first non repeating character in a string c# - three ways

My python implementation: def firstNonRepeatingCharacter(inputString): hashmap = {} for x in inputString: if (x in hashmap): hashmap[x] = hashmap[x] + 1 else: hashmap[x] = 1 for x in inputString: if (hashmap[x] > 1): continue else: return x return "No nonrepeating character found"

for (int index = 0; index < str.Length; index++) { if (str.LastIndexOf(str[index]) == str.IndexOf(str[index])) { return str[index].ToString(); } }

I will have one variable x to store the first non repeating character, variable y as a backup And a set of characters already encountered. I will start from position n to position 0 where n is the lenght of the string. If char(n) is not present in the set, then check if x=char(n), if yes, x = y. If no, y=x and x=char(n). The idea is to keep updating the newest character that has not been repeated and also keeping the second newest character as a backup. In the end return x.

## In Python from collections import Counter def lh(str): lst1 = [] lst2 = [] m = Counter(str) for i, j in m.items(): if j == 1: lst1.append(i) lst2.append(j) print(lst1[0],lst2[0]) lh('aaabbcccdeee') lh('jkshciushgdyiegcigidbircbrot7bRNXBYREICXN')

@Kumar Manish(Your solution sir,) ## My python3 program from collections import Counter def lh(str): lst1 = [] lst2 = [] m = Counter(str) for i, j in m.items(): if j == 1: lst1.append(i) lst2.append(j) if len(lst1) == 0: print('null') else: print(lst1[0], lst2[0]) lh('aaabbcccdeee') lh('jkshciushgdyiegcigidbircbrot7bRNXBYREICXN') lh('aaa')

hash of non repeating characters tied to a double linked list, remove any repeating character from the hash and the list. at the end the head of the list is the answer. you can use the same hash to keep the counters.

public static String findFirstNonRepeatedCharacter(String S) { int[] T = new int[256]; for (int i = 0; i < S.length(); i++) { char next = S.charAt(i); T[next] = T[next] + 1; } for (int i = 0; i < S.length(); i++) { if(T[S.charAt(i)] == 1) return String.valueOf(S.charAt(i)); } return null; }

Three ways to find first non repeating character in a string c# find the code below - public char firstNonRepetitive(string inputString) { int nextOccurrence = 0; char firstDistinctChar = ' '; for (int i = 0; i < inputString.Length; i++) { nextOccurrence = 0; for (int j = (i + 1); j < inputString.Length; j++) { if (inputString[i] == inputString[j]) nextOccurrence++; } if (nextOccurrence == 0) { firstDistinctChar = inputString[i]; break; } } return firstDistinctChar; } Check out amazing two more way - program to find first non repeating character in a string c# - three ways http://www.dotnetbull.com/2013/08/find-first-non-repeating-character-string.html

Hint: use a hash table

public static char getFirstNonRepeatedChar(String s) { List charList = null; char nonRepeatedChar ='?'; if (s != null) { s = s.trim(); charList = new ArrayList(); for (int i=0; i