package string; import java.util.HashMap; import java.util.Map; /** * @ProjectName: leetcode * @Package: string * @ClassName: String389 * @Author: markey * @Description: * @Date: 2020/6/4 22:44 * @Version: 1.0 */ public class String389 { public char findTheDifference(String s, String t) { Map map = new HashMap<>(); for (char c : s.toCharArray()) { map.put(c, map.getOrDefault(c, 0) + 1); } for (char c: t.toCharArray()) { if (map.containsKey(c) && map.get(c) > 0) { map.put(c, map.get(c) - 1); } else { return c; } } return ' '; } }