매일개발

https://www.acmicpc.net/problem/1991

문제 풀이(코드)

import java.util.Scanner;
import java.util.ArrayList;

public class Main {
    public static void printPath(ArrayList<Integer> path) {
        for (int i = 0; i < path.size(); i++) {
            char cur = (char)(path.get(i) + 'A');
            System.out.print(cur);
        }
    }

    public static void preorder(int[][] tree, int row, ArrayList<Integer> path) {
        // 현재 노드 방문 처리
        path.add(tree[row][0]);
        // 왼쪽 노드로 이동
        if (tree[row][1] != -1) preorder(tree, tree[row][1], path);
        // 오른쪽 노드로 이동
        if (tree[row][2] != -1) preorder(tree, tree[row][2], path);
    }

    public static void inorder(int[][] tree, int row, ArrayList<Integer> path) {
        // 왼쪽 노드로 이동
        if (tree[row][1] != -1) inorder(tree, tree[row][1], path);
        // 현재 노드 방문 처리
        path.add(tree[row][0]);
        // 오른쪽 노드로 이동
        if (tree[row][2] != -1) inorder(tree, tree[row][2], path);
    }

    public static void postorder(int[][] tree, int row, ArrayList<Integer> path) {
        // 왼쪽 노드로 이동
        if (tree[row][1] != -1) postorder(tree, tree[row][1], path);
        // 오른쪽 노드로 이동
        if (tree[row][2] != -1) postorder(tree, tree[row][2], path);
        // 현재 노드 방문 처리
        path.add(tree[row][0]);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[][] tree = new int[n][3];

        for (int i = 0; i < n; i++) {
            int row = (int)(sc.next().charAt(0) - 'A');
            tree[row][0] = row;

            int left, right;
            for (int j = 1; j <= 2; j++) {
                char cur = sc.next().charAt(0);
                if (cur == '.') tree[row][j] = -1;
                else tree[row][j] = (int)(cur - 'A');
            }
        }

        ArrayList<Integer> preorderPath = new ArrayList<Integer>();
        preorder(tree, 0, preorderPath);

        ArrayList<Integer> inorderPath = new ArrayList<Integer>();
        inorder(tree, 0, inorderPath);

        ArrayList<Integer> postorderPath = new ArrayList<Integer>();
        postorder(tree, 0, postorderPath);

        printPath(preorderPath);
        System.out.println();
        printPath(inorderPath);
        System.out.println();
        printPath(postorderPath);
        System.out.println();
        
        sc.close();
    }
}

https://www.acmicpc.net/problem/1956

문제 풀이(코드)

import java.util.*;

public class Main {
	static int[][] graph;
	static int v, e, min = Integer.MAX_VALUE;
	static final int INF = (int)1e9;
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		v = scan.nextInt();
		e= scan.nextInt();
		
		graph = new int[v+1][v+1];
		
		for(int i = 0; i <= v; i++)
			Arrays.fill(graph[i],INF);
		
		for(int i = 0; i < e; i++) {
			int a = scan.nextInt();
			int b = scan.nextInt();
			int c = scan.nextInt();
			
			graph[a][b] = Math.min(graph[a][b], c);
		}
		
		for(int k = 1; k <= v; k++)
			for(int i = 1; i <= v; i++)
				for(int j = 1; j <= v; j++)
					graph[i][j] = Math.min(graph[i][j], graph[i][k] + graph[k][j]);
		
		for(int i = 1; i <= v; i++)
			min = Math.min(min, graph[i][i]);
		
		if(min == INF)
			System.out.println(-1);
		else
			System.out.println(min);
		
		scan.close();
	}

}

https://www.acmicpc.net/problem/7569

문제 조건

문제 풀이 (코드)

import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
    private static int N;
    private static int M;
    private static int H;
    private static int box[][][];
    private static boolean visited[][][];
    private static int[] dx = {1, 0, -1, 0, 0, 0};
    private static int[] dy = {0, 1, 0, -1, 0, 0};
    private static int[] dz = {0, 0, 0, 0, 1, -1};
    private static int count = 0;

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);

        M = scan.nextInt();
        N = scan.nextInt();
        H = scan.nextInt();

        box = new int[H + 1][N + 1][M + 1];
        visited = new boolean[H + 1][N + 1][M + 1];

        for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= N; j++) {
                for (int k = 1; k <= M; k++) {
                    box[i][j][k] = scanner.nextInt();
                }
            }
        }

        bfs();

        for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= N; j++) {
                for (int k = 1; k <= M; k++) {
                    if (box[i][j][k] == 0) {
                        System.out.println(-1);
                        return;
                    }
                }
            }
        }

        System.out.println(count);
        
        scan.close();
    }

    private static void bfs() {
        Queue<Point> queue = new LinkedList<>();

        for (int i = 1; i <= H; i++) {
            for (int j = 1; j <= N; j++) {
                for (int k = 1; k <= M; k++) {
                    if (box[i][j][k] == 1) {
                        queue.add(new Point(j, k, i, 0));
                        visited[i][j][k] = true;
                    }
                }
            }
        }

        while (!queue.isEmpty()) {
            Point point = queue.poll();

            count = Math.max(count, point.depth);

            for (int i = 0; i < 6; i++) {
                int x = point.x + dx[i];
                int y = point.y + dy[i];
                int z = point.z + dz[i];

                if (isInArea(x, y, z)) {
                    if (box[z][x][y] == 0 && !visited[z][x][y]) {
                        queue.add(new Point(x, y, z, point.depth + 1));
                        box[z][x][y] = 1;
                        visited[z][x][y] = true;
                    }
                }
            }
        }
    }

    private static boolean isInArea(int x, int y, int z) {
        return x > 0 && x <= N && y > 0 && y <= M && z > 0 && z <= H;
    }

    static class Point {
        private int x;
        private int y;
        private int z;
        private int depth;

        public Point(int x, int y, int z, int depth) {
            this.x = x;
            this.y = y;
            this.z = z;
            this.depth = depth;
        }
    }
}

https://www.acmicpc.net/problem/2606

오늘 풀어볼 문제는 2606번 바이러스 문제이다.

2004년 한국정보올림피라드 지역본선 초등부 3번 문제라는데,

초등학생이 풀 수 있으니까 나도 풀 수 있다!

문제 조건

문제 풀이 (코드)

import java.util.ArrayList;
import java.util.Scanner;

public class Main {

	static ArrayList<Integer>[] network;
	static boolean[] visited;
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		
		int n = scan.nextInt(); 
		network = new ArrayList[n + 1];
		visited = new boolean[n + 1];
		for(int i = 0; i < n + 1; i++) {
			network[i] = new ArrayList<>();
		}
		
		int l = scan.nextInt(); 
		for(int i= 0; i < l; i++){
			int u = scan.nextInt();
			int v = scan.nextInt();
			network[u].add(v);
			network[v].add(u);
		}
		
		DFS(1);

		int rslt = 0;
		for(boolean flag : visited){
			if(flag == true) {
				rslt++;
			}	
		}
		System.out.println(rslt - 1);
		
		scan.close();
	}
	
	private static void DFS(int u) {
		visited[u] = true;
		
		for(int v : network[u]){
			if(visited[v] == false) {
				DFS(v);
			}	
		}
	}

}