Check if a string is Isogram or not

Problem Statement - link #

Given a string S of lowercase alphabets, check if it is isogram or not. An Isogram is a string in which no letter occurs more than once.

Your Task: This is a function problem. You only need to complete the function isIsogram() that takes a string as a parameter and returns either true or false.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(Number of distinct characters)

Examples #

Example 1:

Input:
S = machine
Output: 1
Explanation: machine is an isogram
as no letter has appeared twice. Hence
we print 1.

Example 2:

Input:
S = geeks
Output: 0
Explanation: geeks is not an isogram
as 'e' appears twice. Hence we print 0.

Constraints #

• 1 <= |s1|, |s2| <= 10^3

Solutions #

class Solution{
    public:
    //Function to check if a string is Isogram or not.
    bool isIsogram(string s)
    {
        //Your code here
        unordered_set<char> us;
        for(char c: s){
            if(us.find(c)!=us.end()) return false;
            us.insert(c);
        }
        return true;
    }
};