[프로그래머스][JAVA] H-Index (정렬, 이진탐색)

import java.util.*;
 
class Solution {
    public int solution(int[] citations) {
        int h = 0;
        Arrays.sort(citations);
        
        int len = citations.length;
        
        // System.out.println(Arrays.binarySearch(citations, 3));
        
        while(true){
            int idx = Arrays.binarySearch(citations, h);
            if(idx<0){
                idx = -(idx+1);
            }
            else{
                while(idx>=1 && citations[idx]==citations[idx-1]){
                    idx--;
                }
            }
            
            if(h<=len-idx){
                h++;    
            }
            else{
                h--;
                break;
            }
        }
        
        // while(i>=0){
        //     int curr = citations[i];
        //     while(i>=0 && citations[i] == curr){
        //         i--;
        //     }
        //     int num = len-i;
        //     if(curr<=num){
        //         answer = curr;
        //         break;
        //     }
        // }
        
        
        return h;
    }
}

 

 

import java.util.*;
 
class Solution {
    public int solution(int[] citationsInput) {
        int answer = 0;
        
        ArrayList<Integer> citations = new ArrayList<>();
        for(int c : citationsInput){
            citations.add(c);  
        }
        
        Collections.sort(citations);
        Collections.reverse(citations);
        
        int accum = 0;
        for(int c : citations){
            if(accum<c) accum++;
            else{
                break;
            }
        }
        
        
        return accum;
    }
}