Longest Substring With at Most Two Distinct Characters
Created: March 16, 2019 by [lek-tin]
Last updated: March 16, 2019
Given a string s, find the length of the longest substring t that contains at most 2 distinct characters.
Example 1
Input: "eceba"
Output: 3
Explanation: t is "ece" which its length is 3.
Example 2
Input: "ccaabbb"
Output: 5
Explanation: t is "aabbb" which its length is 5.
Solution
class Solution {
public int lengthOfLongestSubstringTwoDistinct(String s) {
HashMap<Character, Integer> countMap = new HashMap<Character, Integer>();
int left = 0;
int max = 0;
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
countMap.put(c, countMap.getOrDefault(c, 0) + 1);
while (countMap.size() > 2) {
char leftChar = s.charAt(left);
countMap.put(leftChar, countMap.getOrDefault(leftChar, 0) - 1);
if (countMap.get(leftChar) == 0) {
countMap.remove(leftChar);
}
left++;
}
max = Math.max(max, i - left + 1);
}
return max;
}
}