https://www.acmicpc.net/problem/1992

쿼드트리.java

import java.util.*;

public class Main {
    static int[][] field;
    static StringBuilder sb = new StringBuilder();
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        field = new int[n][n];
        for(int i=0; i<n; i++){
            String[] temp = sc.next().split("");
            for(int j=0; j<n; j++)
                field[i][j] = Integer.parseInt(temp[j]);
        }
        coleredPaper(n, 0, 0);
        System.out.print(sb);
        
    }
    static void coleredPaper(int n, int x, int y){
        if(isSame(n, x, y)){
            sb.append(field[y][x]);
            return;
        }
        sb.append("(");
        coleredPaper(n/2, x, y);
        coleredPaper(n/2, x+n/2, y);
        coleredPaper(n/2, x, y+n/2);
        coleredPaper(n/2, x+n/2, y+n/2);
        sb.append(")");
    }
    static boolean isSame(int n, int x, int y){
        int criteria = field[y][x];
        for(int i=y; i<y+n; i++)
            for(int j=x; j<x+n; j++)
                if (criteria!=field[i][j]) return false;
        return true;
    }
}