Repeating Character - First Appearance Leftmost

Problem Statement - link #

You are given a string S (both uppercase and lowercase characters). You need to print the repeated character whose first appearance is leftmost.

Your Task: This is a function problem. You only need to complete the function repeatedCharacter() that takes a string as a parameter and returns the index of the character. If no character repeats then return -1.

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

Examples #

Example 1:

Input:
S = geeksforgeeks
Output: g
Explanation: We see that both e and g
repeat as we move from left to right.
But the leftmost is g so we print g.

Example 2:

Input:
S = abcd
Output: -1
Explanation: No character repeats so
we print -1.

Constraints #

• 1 <=|S| ≤ 100

Solutions #

class Solution{
    public:
    //Function to find repeated character whose first appearance is leftmost.
    int repeatedCharacter (string s) 
    { 
        //Your code here
        unordered_map<char, int> um;
        for(char c: s) um[c]++;
        for(int i=0; i<s.size(); i++)
            if(um[s[i]]>1) return i;
        return -1;
    } 
};