Easy and clear Java solution

• The reason I do left =i right =i and left=i right=i+1 is there are two kinds palindromes one is like "abcba" and another is like "abccba".

``````    int start=0, end=0;
int maxLen = 1;
for(int i = 0; i < s.length(); i++){
int left = i;
int right = i;
while(left>-1 && right<s.length() && s.charAt(left) == s.charAt(right)){
left--;
right++;
}
if(maxLen<right-left+1){
maxLen = right - left + 1;
start = left+1;
end = right-1;
}
left = i;
right = i+1;
while(left>-1 && right<s.length() && s.charAt(left) == s.charAt(right)){
left--;
right++;
}
if(maxLen<right-left+1){
maxLen = right - left + 1;
start = left+1;
end = right-1;
}

}
return s.substring(start,end+1);``````

• your code is great.

But I found an error when calculating maxLen.

if should be

maxLen < right-left-1

• Let's say input is "qweabccbaiop", so the longest panlidrome is "abccba" whose start index is 3, end index is 8 and length is 6, therefore, length = right-left+1.

Happy Thanksgiving day.

• when you found "abccba", the left is actually pointing at "e", and right is pointing "i", that's why I suggest "right-left-1". I ran your code in eclipse, and it showed what i said here.

Thanks for the quick reply and Happy Thanksgiving!

• haha, you are right. It got AC so I did not test in Eclipse, thanks for pointing out error

• smart! we just need to keep track of the len, start and end, we don't need to actually generate the substring as an intermediate process.

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