[BOJ 17140] 이차원 배열과 연산 (JAVA)

https://www.acmicpc.net/problem/17140

17140번: 이차원 배열과 연산

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Array;
import java.util.*;

public class P17140 {
    static int r, c, k;
    static int ans=-1;
    static ArrayList<ArrayList<Integer>> board=new ArrayList<>(3);
    public static void main(String[] args) throws IOException {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(br.readLine());
        r=Integer.parseInt(st.nextToken())-1;
        c=Integer.parseInt(st.nextToken())-1;
        k=Integer.parseInt(st.nextToken());
        for (int i=0; i<3; i++){
            st=new StringTokenizer(br.readLine());
            board.add(new ArrayList<>());
            for (int j=0; j<3; j++) {
                board.get(i).add(Integer.parseInt(st.nextToken()));
            }
        }
        for (int t=0; t<=100; ++t) {
            int rowSize = board.size();
            int colSize = board.get(0).size();
            if (r < rowSize && c < colSize && board.get(r).get(c) == k) {
                ans = t;
                break;
            }
            if (rowSize >= colSize) {
                RCalc();
            } else {
                CCalc();
            }
            /*
            System.out.println();
            for (int i=0; i<board.size(); i++){
                System.out.println(board.get(i).toString());
            }
            */
        }
        System.out.println(ans);
    }
    public static void RCalc(){         //행 단위
        int maxSize=0;
        for (int i=0; i<board.size(); i++){
            int cnt=0;
            ArrayList<Integer> temp=new ArrayList<>();
            PriorityQueue<Infos> pq=new PriorityQueue<>();
            Map<Integer, Integer> m=new HashMap<>();
            for (int j=0; j<board.get(i).size(); j++){
                int item=board.get(i).get(j);
                if (item!=0) {
                    int count = m.containsKey(item) ? m.get(item) : 0;
                    m.put(item, count + 1);
                }
            }
            for (Integer itg: m.keySet()){
                pq.add(new Infos(itg, m.get(itg)));
            }
            while (!pq.isEmpty()){
                cnt++;
                if (cnt>100){
                    break;
                }
                Infos info=pq.poll();
                temp.add(info.num); temp.add(info.cnt);
            }
            board.get(i).clear();
            board.get(i).addAll(temp);
            maxSize=board.get(i).size()>maxSize?board.get(i).size():maxSize;
        }
        for (int i=0; i<board.size(); i++){
            int len=board.get(i).size();
            if (len<maxSize){
                for (int j=0; j<maxSize-len; j++){
                    board.get(i).add(0);
                }
            }
        }
    }

    public static void CCalc(){
        for (int i=0; i<board.get(0).size(); i++){
            int cnt=0;
            ArrayList<Integer> temp=new ArrayList<>();
            PriorityQueue<Infos> pq=new PriorityQueue<>();
            Map<Integer, Integer> m=new HashMap<>();
            for (int j=0; j<board.size(); j++){
                int item=board.get(j).get(i);
                if (item!=0) {
                    int count = m.containsKey(item) ? m.get(item) : 0;
                    m.put(item, count + 1);
                }
            }
            for (Integer itg: m.keySet()){
                pq.add(new Infos(itg, m.get(itg)));
            }
            while (!pq.isEmpty()){
                cnt++;
                if (cnt>100){
                    break;
                }
                Infos info=pq.poll();
                temp.add(info.num); temp.add(info.cnt);
            }
            if (board.size()<temp.size()){
                int len=temp.size()-board.size();
                for (int k=0; k<len; k++){
                    board.add(new ArrayList<>(Collections.nCopies(board.get(0).size(),0)));
                }
            }
            for (int k=0; k<board.size(); k++){
                if (k>=temp.size()){
                    board.get(k).set(i, 0);
                }
                else{
                    board.get(k).set(i, temp.get(k));
                }
            }
        }
    }

    public static class Infos implements Comparable<Infos>{
        int num;
        int cnt;
        public Infos(int num, int cnt){
            this.num=num;
            this.cnt=cnt;
        }
        @Override
        public int compareTo(Infos i){
            if (i.cnt==this.cnt){
                return this.num>=i.num?1:-1;
            }
            return this.cnt>=i.cnt?1:-1;
        }
    }
}

풀이가 너무 더럽다..

https://kora1492.tistory.com/14

백준 17140 JAVA - 2차원 배열과 연산

잘만 생각해보면 map을 쓸 필요, pq도 쓸 필요도 없다!

 

Infos 객체를 담는 arraylist 객체를 sort 하면 우선순위에 맞는 배열이 나온다. 

그리고 board를 board[101][101] 의 2차원 배열로 생성한다.

수의 횟수를 셀때는 1부터 100까지 수가 있을 수 있다는 점을 이용해, cnt[101] 배열을 만들어 각 인덱스(수)에 맞는 수 갯수를 세주면 된다!!