819.最常见的单词

819.最常见的单词

题目描述：

解法：求出段落中所有的单词

代码：

class Solution {
    
    
    public String mostCommonWord(String paragraph, String[] banned) {
    
    

        String rest = ""; //函数返回值
        paragraph = paragraph.toLowerCase(); //转为小写  
        int pre = 0;   // paragraph.substring(pre,i)
        int len = paragraph.length(); 
        int count = 0; //标记最多出现次数
        Set<String> set = new HashSet<>();// 便于检验禁止单词
        for(String s: banned){
    
    
            set.add(s);
        }
        //key是 paragraph 中的单词，value是单词出现的次数
        Map<String, Integer> map = new HashMap<>();        
        for(int i = 0; i < len; i++){
    
    
            pre = i;
            
            while(i < len && paragraph.charAt(i) <= 'z' && paragraph.charAt(i) >= 'a'){
    
    
                i++;
            }
            if(i <= len){
    
    
                String str = paragraph.substring(pre,i);
                map.put(str, map.getOrDefault(str, 0) + 1);
                if(map.get(str) > count && !set.contains(str)){
    
    
                    count = map.get(str);
                    rest = str;
                }
                while(i < len && (paragraph.charAt(i) < 'a' || paragraph.charAt(i) > 'z')){
    
    
                    i++;
                }
                i--;
            }

        }

        return rest;
    }
}