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refactor: LongestNonRepetitiveSubstring (#5421)

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* refactor: LongestNonRepetitiveSubstring

* checkstyle: fix formatting

---------

Co-authored-by: alxkm <alx@alx.com>
This commit is contained in:
Alex Klymenko
2024-08-28 18:40:27 +02:00
committed by GitHub
parent c413f3c6b2
commit b2815db5cd
2 changed files with 39 additions and 39 deletions
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55
src/main/java/com/thealgorithms/strings/LongestNonRepetitiveSubstring.java
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@ -3,47 +3,40 @@ package com.thealgorithms.strings;
import java.util.HashMap;
import java.util.Map;
/**
* Class for finding the length of the longest substring without repeating characters.
*/
final class LongestNonRepetitiveSubstring {
private LongestNonRepetitiveSubstring() {
}
/**
* Finds the length of the longest substring without repeating characters.
*
* @param s the input string
* @return the length of the longest non-repetitive substring
*/
public static int lengthOfLongestSubstring(String s) {
int max = 0;
int maxLength = 0;
int start = 0;
int i = 0;
Map<Character, Integer> map = new HashMap<>();
Map<Character, Integer> charIndexMap = new HashMap<>();
while (i < s.length()) {
char temp = s.charAt(i);
for (int i = 0; i < s.length(); i++) {
char currentChar = s.charAt(i);
// adding key to map if not present
if (!map.containsKey(temp)) {
map.put(temp, 0);
} else if (s.charAt(start) == temp) {
start++;
} else if (s.charAt(i - 1) == temp) {
if (max < map.size()) {
max = map.size();
}
map = new HashMap<>();
start = i;
i--;
} else {
if (max < map.size()) {
max = map.size();
}
while (s.charAt(start) != temp) {
map.remove(s.charAt(start));
start++;
}
start++;
// If the character is already in the map and its index is within the current window
if (charIndexMap.containsKey(currentChar) && charIndexMap.get(currentChar) >= start) {
// Move the start to the position right after the last occurrence of the current character
start = charIndexMap.get(currentChar) + 1;
}
i++;
// Update the last seen index of the current character
charIndexMap.put(currentChar, i);
// Calculate the maximum length of the substring without repeating characters
maxLength = Math.max(maxLength, i - start + 1);
}
if (max < map.size()) {
max = map.size();
}
return max;
return maxLength;
}
}