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LongestSubstringWithNoRepeatingCharacters.java
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LongestSubstringWithNoRepeatingCharacters.java
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package Leetcode;
import java.util.HashMap;
import java.util.Map;
/**
* @author kalpak
*
* Given a string s, find the length of the longest substring without repeating characters.
*
* Example 1:
*
* Input: s = "abcabcbb"
* Output: 3
* Explanation: The answer is "abc", with the length of 3.
* Example 2:
*
* Input: s = "bbbbb"
* Output: 1
* Explanation: The answer is "b", with the length of 1.
* Example 3:
*
* Input: s = "pwwkew"
* Output: 3
* Explanation: The answer is "wke", with the length of 3.
* Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.
* Example 4:
*
* Input: s = ""
* Output: 0
*
*
* Constraints:
*
* 0 <= s.length <= 5 * 104
* s consists of English letters, digits, symbols and spaces.
*/
public class LongestSubstringWithNoRepeatingCharacters {
public static int lengthOfLongestSubstring(String s) {
if(s.length() == 0)
return 0;
Map<Character, Integer> map = new HashMap<>();
int result = Integer.MIN_VALUE;
int i = 0;
int j = 0;
while(j < s.length()) {
map.put(s.charAt(j), map.getOrDefault(s.charAt(j), 0) + 1);
if(map.size() == j-i+1) {
result = Math.max(result, j - i + 1);
} else if(map.size() < j - i + 1) { // some characters are repeating since window size is larger than the map
while(map.size() < j-i+1) {
map.put(s.charAt(i), map.get(s.charAt(i)) - 1);
if(map.get(s.charAt(i)) == 0)
map.remove(s.charAt(i));
i++;
}
}
j++;
}
return result;
}
public static void main(String[] args) {
System.out.println(lengthOfLongestSubstring("abcabcbb"));
System.out.println(lengthOfLongestSubstring("bbbb"));
System.out.println(lengthOfLongestSubstring("pwwkew"));
}
}