Java：split() 过滤
class Solution {
public String mostCommonWord(String paragraph, String[] banned) {
String s = paragraph.replaceAll("\\p{Punct}", " "); // 去除所有标点符号
String arr[] = s.split(" +"); // "a, a, a, a, b,b,b,c, c" 遇到这种案例就很恶心，不按照正规的格式来出牌！
Map<String, Integer> map = new HashMap<>();
Set<String> set = new HashSet<>();
for (String str : banned) {
set.add(str);
}
for (int i = 0; i < arr.length; ++i) {
String ss = arr[i].toLowerCase();
if (!set.contains(ss)) {
map.put(ss, map.getOrDefault(ss, 0) + 1);
}
}
List<String> list = new ArrayList<>(map.keySet());
Collections.sort(list, (a, b) -> map.get(b).compareTo(map.get(a)));
return list.get(0);
}
}
Java：直接筛选字符
class Solution {
public String mostCommonWord(String paragraph, String[] banned) {
Set<String> bannedSet = new HashSet<String>();
for (String word : banned) {
bannedSet.add(word);
}
int maxFrequency = 0;
Map<String, Integer> frequencies = new HashMap<String, Integer>();
StringBuffer sb = new StringBuffer();
int length = paragraph.length();
for (int i = 0; i <= length; i++) {
if (i < length && Character.isLetter(paragraph.charAt(i))) {
sb.append(Character.toLowerCase(paragraph.charAt(i)));
} else if (sb.length() > 0) {
String word = sb.toString();
if (!bannedSet.contains(word)) {
int frequency = frequencies.getOrDefault(word, 0) + 1;
frequencies.put(word, frequency);
maxFrequency = Math.max(maxFrequency, frequency);
}
sb.setLength(0);
}
}
String mostCommon = "";
Set<Map.Entry<String, Integer>> entries = frequencies.entrySet();
for (Map.Entry<String, Integer> entry : entries) {
String word = entry.getKey();
int frequency = entry.getValue();
if (frequency == maxFrequency) {
mostCommon = word;
break;
}
}
return mostCommon;
}
}
