백준 정렬 - 2108번 : 통계학

https://www.acmicpc.net/problem/2108

2108번: 통계학

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계수 정렬을 이용해 정렬하고 문제를 풀었는데 음수 index 및 자료형을 처리하는게 까다로웠다.

import java.io.*;
import java.util.*;
public class Main {
	
	public static void main(String[] args) throws IOException{
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
        int[] a = new int[n];
        double sum=0;
        for(int i=0; i<n; i++){
            a[i] = Integer.parseInt(br.readLine());
            sum+=(double)a[i];
            
        }
        br.close();
        long avg = Math.round(sum/(double)n);
        int mid;
        int count=0;
        int r;
        int[] range = new int[8001];
        int tidx = 0;
        for(int i=0; i<n; i++) {
        	tidx = a[i]+4000;
            range[tidx]++;
        }
        int max = -1;
        for(int i=1; i<range.length; i++) {
        	if(max<range[i]) {
        		max = range[i];
        	}
        }
        for(int i=1; i<range.length; i++) {
        	range[i] +=range[i-1];
        }
        int[] ans = new int[n];
        for(int i=0; i<n; i++) {
        	tidx = a[i]+4000;
        	ans[--range[tidx]] = a[i];
        }
        
        HashMap<Integer, Integer> time = new HashMap<>();
        int tmax = -1;
        for(int i=0; i<n; i++) {
        	if(time.get(ans[i])==null) {
        		time.put(ans[i], 1);
        	}
        	else time.put(ans[i], time.get(ans[i])+1);
        	if(time.get(ans[i])>tmax) tmax = time.get(ans[i]);
        }
        ArrayList<Integer> temp = new ArrayList<>();
    	for(int i=0; i<n; i++) {
        	if(time.get(ans[i])==tmax) {
        		if(!temp.contains(ans[i])) temp.add(ans[i]);
        	}
        }
    	if(temp.size()==1) {
    		count = temp.get(0);
    	}
    	else count = temp.get(1);
        mid = ans[n/2];
        int min = ans[0];
        int maxs = ans[ans.length-1];
        r = maxs-min;
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        bw.write(avg+"\n");
        bw.write(mid+"\n");
        bw.write(count+"\n");
        bw.write(r+"\n");
        bw.close();
    }
	
}