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.
题意：
给定字符串，找出至多包含两种字符的最长子串。
思路：
j
“e c e b a”
i e-0
i c-1
i e-2
-------map.size()<= 2
i b-3 此时移动 j
代码：
class Solution {
public int lengthOfLongestSubstringTwoDistinct(String s) {
if(s.length() < 2) return s.length();
HashMap<Character, Integer> map = new HashMap<>();
int result = 0;
int j = 0;
for(int i = 0; i < s.length(); ){
char c = s.charAt(i);
if(map.size() <= 2){
map.put(c, i);
i++;
}
if(map.size() > 2){
int leftMost = s.length();
for(int n : map.values()){
leftMost = Math.min(leftMost, n);
}
map.remove(s.charAt(leftMost));
j = leftMost + 1;
}
result = Math.max(result, i - j );
}
return result;
}
}