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LeetCode

Approach 1: Custom Sort

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class Solution {
    public String[] reorderLogFiles(String[] logs) {
        Arrays.sort(logs,(log1,log2)->{
            String[] split1=log1.split(" ",2);
            String[] split2=log2.split(" ",2);
            boolean isDigit1=Character.isDigit(split1[1].charAt(0));
            boolean isDigit2=Character.isDigit(split2[1].charAt(0));
            if(!isDigit1&&!isDigit2){
                int cmp=split1[1].compareTo(split2[1]);
                if(cmp==0) return split1[0].compareTo(split2[0]);
                else return cmp;
            }
            return isDigit1?(isDigit2?0:1):-1; /* 1: descending order, -1: ascending order*/
        });
        return logs;
    }
}

Approach 2: TreeMap + PriorityQueue

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class Solution {
    public String[] reorderLogFiles(String[] logs) {
        List<String> ls=new ArrayList<>();
        
        Map<String,Queue<String>> map=new TreeMap<>();
        for(String log:logs){
            String[] split=log.split(" ",2);
            String id=split[0];
            String content=split[1];
            if(Character.isLetter(content.charAt(0))){
                if(!map.containsKey(content)){
                    map.put(content,new PriorityQueue<String>());
                }
                map.get(content).offer(id);
            }else{
                ls.add(log);
            }
        }
        
        int idx=0;
        for(String content:map.keySet()){
            Queue<String> q=map.get(content);
            while(!q.isEmpty()){
                String id=q.poll();
                ls.add(idx,id+" "+content);
                idx++;
            }
        }
        return ls.toArray(new String[0]);
    }
}

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