leetcode-algorithms/src/LongestNiceSubstring.java at master · anishLearnsToCode/leetcode-algorithms · GitHub

40 lines (36 loc) · 1.29 KB

import java.util.HashSet;

import java.util.Set;

public class LongestNiceSubstring {

public String longestNiceSubstring(String s) {

String longestNiceSubString = "";

Set<Character> alphabets = new HashSet<>();

for (int i = 0 ; i < s.length() ; i++) {

for (int j = i ; j < s.length() ; j++) {

alphabets.add(s.charAt(j));

if (containsBotLowerAndUpperCase(alphabets) && j - i + 1 > longestNiceSubString.length()) {

longestNiceSubString = s.substring(i, j + 1);

}

alphabets.clear();

}

return longestNiceSubString;

}

private boolean containsBotLowerAndUpperCase(Set<Character> alphabets) {

for (char alphabet : alphabets) {

if (!alphabets.contains(inverse(alphabet))) {

return false;

}

return true;

}

private char inverse(char c) {

return Character.isLowerCase(c) ? Character.toUpperCase(c) : Character.toLowerCase(c);

}

private Set<Character> getCharacters(String s, int start, int end) {

final Set<Character> set = new HashSet<>();

for (int index = start ; index <= end ; index++) {

set.add(s.charAt(index));

}

return set;

}

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