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First Unique Character in a String
Problem : First Unique Character in a String
Problem Link :
Companies Asked : Amdocs, OLA
Approach:
Count the frequency of the characters in the given string.
Now for each ith character, check the frequency of appearance.
If the frequency of a character is 1, then return the ith character/ith index.
If there is no character whose frequency is greater than 1, then return # / -1.
Time and Space Complexity:
Time Complexity: O(N)
Space Complexity: O(1)
Code [C++]
#include <bits/stdc++.h>
char findNonRepeating(string str) {
vector<int>freq(26, 0);
int n = str.size();
for(int i=0; i<n; i++){
freq[str[i]-'a']++;
}
for(int i=0; i<n; i++){
if(freq[str[i]-'a'] == 1) return str[i];
}
return '#';
}