Permutation_in_String.java

//Leetcode 567. Permutation in String
//Question - https://leetcode.com/problems/permutation-in-string/

classSolution {
publicbooleancheckInclusion(Strings1, Strings2) {
if(s1.length()==0 && s2.length()==0) returntrue;
elseif(s1.length()==0) returntrue;
elseif(s2.length()==0) returnfalse;
//We are supposed to check if 's2' contains the anagram of 's1'

HashMap<Character,Integer> freqTable = newHashMap<>();
intfreq = -1;
for(inti=0;i<s1.length();i++){
charcurr = s1.charAt(i);
freq = freqTable.getOrDefault(curr,0);
freq++;
freqTable.put(curr,freq);
 }
//System.out.println(freqTable);
intend = 0;
intstart = 0;
intcounter = freqTable.size();

while(end < s2.length()){
charendChar = s2.charAt(end);

if(freqTable.containsKey(endChar)){
freq = freqTable.get(endChar);
freq--;
freqTable.put(endChar,freq);
if(freq==0) counter--;
 }

end++;

while(counter==0){
charstartChar = s2.charAt(start);

if(end-start==s1.length()){
returntrue;
 }

if(freqTable.containsKey(startChar)){
freq = freqTable.get(startChar);
freq++;
freqTable.put(startChar,freq);
if(freq>0) counter++;
 }
start++;
 }
 }
returnfalse;
 }
}