careercup1.3: remove duplicate without extra space.

First, ask yourself, what does the interviewer mean by an additional bu#er? Can we use an

additional array of constant size?

Algorithm—No (Large) Additional Memory:

1. For each character, check if it is a duplicate of already found characters.

2. Skip duplicate characters and update the non duplicate characters.

Time complexity is O(N2)

Test Cases:

1. String does not contain any duplicates, e.g.: abcd

2. String contains all duplicates, e.g.: aaaa

3. Null string

4. String with all continuous duplicates, e.g.: aaabbb

package careercup;

import java.util.Arrays;

public class test1 {

public static String checkUnique(char[] s) {
if(s.length<=1) return new String(s);

int tail = 1;
for(int i=1; i<s.length; i++){
int j;
for(j=0; j<tail; j++){
if(s[i]==s[j]){
break;
}
}
if(j==tail){
s[tail++] = s[i];
}
}
return new String(s, 0, tail);
}

public static void main(String[] args){
String s = "abcafasdfgasghfgjkghkfgkffasfasf";
System.out.println( checkUnique(s.toCharArray()) );
}
}