repeated substring of length k

repeated substring of length k

  October 11, 2017    

---

Problem:

find if it is possible to convert it to a string that is repetition of substring with k characters. To convert, we can replace one substring of length k with k characters

Idea was to put all substring into a map 
if there is more than 2 substring then not possible.
if only 2 then the occurrence of one substring should be 1 or i/k -1 as we can only afford 1 diff substring
    
Code:

public static boolean repeatedSubString(String s,int k)
{
if(s.length()%k!=0)
return false;
Map<String,Integer> map=new HashMap<String,Integer>();
for(int i=0;i<s.length();i+=k)
{
String str=s.substring(i,i+k);
if(map.containsKey(str))
map.put(str,map.get(str)+1);
else
map.put(str,1);
}
if(map.size()==1)
return true;
if(map.size()>2)
return false;
Map.Entry<String,Integer> entry=map.entrySet().iterator().next();
 //String key= entry.getKey();
 int ocu=entry.getValue();
if(ocu==1 || ocu==(s.length()/k -1))
return true;
return false;
}