백준_14880_스타트와링크

import java.io.*;
import java.util.*;

public class Main {
    static int N;
    static int[][] S;
    static boolean[] selected;
    static int ans = Integer.MAX_VALUE;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        N = Integer.parseInt(br.readLine());
        S = new int[N][N];
        selected = new boolean[N];

        for(int i = 0; i < N; i++){
            StringTokenizer st = new StringTokenizer(br.readLine());
            for(int j = 0; j < N; j++){
                S[i][j] = Integer.parseInt(st.nextToken());
            }
        }
        dfs(0, 0);

        System.out.print(ans);
    }

    static void dfs(int idx, int size){
        if (size == N / 2) {
            ans = Math.min(ans, calculateDifference());
            return;
        }

        for(int i = idx; i < N; i++){
            selected[i] = true;
            dfs(i + 1, size + 1);
            selected[i] = false;
        }
    }

    static int calculateDifference(){
        int start = 0;
        int link = 0;

        for(int i = 0; i < N; i++){
            for (int j = 0; j < N; j++) {
                if (selected[i] && selected[j]) {
                    start += S[i][j];
                } else if (!selected[i] && !selected[j]) {
                    link += S[i][j];
                }
            }
        }
        return Math.abs(start - link);
    }
}

조건식

	for(int i = 0; i < N; i++){
        if (selected[i]) {
            for (int j = 0; j < N; j++) {
                if (selected[j]) {
                    start += S[i][j];
                }
            }
        } else {
            for (int j = 0; j < N; j++) {
                if (!selected[j]) {
                    link += S[i][j];
                }
            }
        }
    }

• 처음엔 이렇게 스파게티 코드로 작성 -> 비효율적

	for(int i = 0; i < N; i++){
    	for (int j = 0; j < N; j++) {
        	if (selected[i] && selected[j]) {
            	start += S[i][j];
            } else if (!selected[i] && !selected[j]) {
              	link += S[i][j];
            }
         }
      }