text 最多有两个不同字符的最长子串 - 最长子串，最多有两个不同的字符

Posted 2021-04-28

public static int longestSubstringOnlyTwoDistinctChar(String s) {
		if(s==null || s.length()==0) return 9;
		Map<Character,Integer> map = new HashMap<>();
		int res = 0 ;
		int start = 0 ;
		for(int i =0 ; i < s.length() ;) {
			char cur = s.charAt(i);
			if(map.isEmpty()) {
				map.put(cur, 1);
			}else if(!map.containsKey(cur)) {
				if(map.entrySet().size()==2) {
					res = res>(i-start)?res:(i-start);
					map.remove(s.charAt(start));
					int temp = start;
					while(s.charAt(temp)==s.charAt(start)) temp++;
					start = temp;
				}
				map.put(cur, 1);
			}else if(map.get(cur)!=null) {
				map.replace(cur, map.get(cur)+1);
			}
			i++;
		}
		return res;
	}