Question

GoldMan Sachs | Recent Interview Experiences | Coderpad | SDE | Set-21

Answer 1

CoderPad question of Goldman Sachs - 29th April 2022
Interviewer was very helpful, and question was also of easy level.
Q. Return the start index and length of the longest substring having identical characters in a given String.
i/p : S = "aabbbbbccddb"
o/p: [2,5]
explaination : As longest substring is 'bbbbb' of length 5 and start index as 2
i/p: S = "aabbb22rrrrr345571111111"
o/p: [17,7]
explaination : As '1111111' is the longest substring of length 7 and start index =17

I used sliding window to solve this. Please comment for the solution.

public class GSLongestSubString {
    public static void main(String[] args){
        String s1 = "aabbbbbccddb";
        String s2 = "aabbb22rrrrr345571111111";
        String s3 = "aaaabbeedddd";
        System.out.println("\n----------------"+"For Given String: "+s1+"----------------");
        callLongestSubstring(s1);
        System.out.println("\n----------------"+"For Given String: "+s2+"----------------");
        callLongestSubstring(s2);
        System.out.println("\n----------------"+"For Given String: "+s3+"----------------");
        callLongestSubstring(s3);
    }
    public static void callLongestSubstring(String s){
        int maxLen=0,start=0,end=0,len=0,startIndex=0;
        while(end+1!=s.length()){
            if(s.charAt(start)==s.charAt(end))
            {
                end++;
                len=end-start;
            }
            else
                start=end;
            if(maxLen<len)
            {
                if(end==s.length()-1)
                    maxLen=len+1;
                else
                    maxLen=len;
                startIndex=start;
            }
            System.out.println("start: "+start+" end: "+end+"  len: "+len+"  maxLen: "+
                    maxLen+"  startIndex: "+startIndex);
        }
        System.out.println("Start Index= "+startIndex+" Longest Length= "+maxLen);
    }
}