[HackerRank] Bomberman Game

HackerRank : The Bomberman Game

Question

Complete the bomberMan function in the editory below. It should return an array of strings that represent the grid in its final state.

bomberMan has the following parameter(s):

n: an integer, the number of seconds to simulate grid: an array of strings that represents the grid

Solution

(1) 첫번째 풀이 (오답)

• 방법
  • 짝수일 경우, 전체 String 폭탄 설치
  • 홀수일 경우, bomberMan(n-2, grid) 호출
• 소스코드

   public static string ReplaceAt(string input, int index, char newChar)
    {
        char[] builder = input.ToCharArray();
        builder[index] = newChar;
        return new string(builder);
    }
  
    public static void detonateBomb(string[] grid) {       
        for (int row = 0; row < grid.Length; row ++)
        {        
            for (int col = 0; col < grid[row].Length; col++)
            {
                if (grid[row][col] == 'O')
                {
                    grid[row] = ReplaceAt(grid[row], col, '.');
  
                    if (row - 1 >= 0 && grid[row -1][col] == 'x')
                        grid[row - 1] = ReplaceAt(grid[row - 1], col, '.');
  
                    if (row + 1 <= grid.Length - 1 && grid[row +1][col] == 'x')
                        grid[row + 1] = ReplaceAt(grid[row + 1], col, '.');
  
                    if (col -1 >= 0 && grid[row][col - 1] == 'x')
                        grid[row] = ReplaceAt(grid[row], col - 1, '.');
  
                    if (col + 1 <= grid[row].Length -1 && grid[row][col + 1] == 'x')
                        grid[row] = ReplaceAt(grid[row], col + 1, '.');
                }
            }
        }
    }
  
    public static void plantBomb(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('.', 'x');
        }
    }
  
    public static string[] plantBombAll(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('.', 'O');
        }
        return grid;
    }
  
    public static void cleanBomb(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('x', 'O');
        }
    }
  
    // Complete the bomberMan function below.
    static string[] bomberMan(int n, string[] grid) {
        if (n % 2 == 0)
            return plantBombAll(grid); 
  
        if (n == 1)
            return grid;       
  
        plantBomb(grid);
        detonateBomb(grid);    
        cleanBomb(grid);
  
        return bomberMan(n - 2, grid);
    }
  

(2) 두번째 풀이 (정답)

• 방법
  • 짝수일 경우, 전체 String 폭탄 설치
  • 홀수일 경우, 3,7,11회차는
    • 3,7,11회차는 detonateBomb(grid); 1회 call
    • 5,9,13회차는 detonateBomb(grid); 2회 call
• 결과
  • Terminated due to timeout
• 소스코드

   private static string ReplaceAt(string input, int index, char newChar)
    {
        char[] builder = input.ToCharArray();
        builder[index] = newChar;
        return new string(builder);
    }
  
    private static void explodeBomb(string[] grid) {       
        for (int row = 0; row < grid.Length; row ++)
        {        
            for (int col = 0; col < grid[row].Length; col++)
            {
                if (grid[row][col] == 'O')
                {
                    grid[row] = ReplaceAt(grid[row], col, '.');
  
                    if (row - 1 >= 0 && grid[row -1][col] == 'x')
                        grid[row - 1] = ReplaceAt(grid[row - 1], col, '.');
  
                    if (row + 1 <= grid.Length - 1 && grid[row +1][col] == 'x')
                        grid[row + 1] = ReplaceAt(grid[row + 1], col, '.');
  
                    if (col -1 >= 0 && grid[row][col - 1] == 'x')
                        grid[row] = ReplaceAt(grid[row], col - 1, '.');
  
                    if (col + 1 <= grid[row].Length -1 && grid[row][col + 1] == 'x')
                        grid[row] = ReplaceAt(grid[row], col + 1, '.');
                }
            }
        }
    }
  
    private static void plantBomb(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('.', 'x');
        }
    }
  
    public static string[] plantBombAll(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('.', 'O');
        }
        return grid;
    }
  
    public static void detonateBomb(string[] grid)
    {
        plantBomb(grid);
        explodeBomb(grid);    
        cleanBomb(grid);
    }
  
  
    public static void cleanBomb(string[] grid) {
        for (int row = 0; row < grid.Length; row ++)
        {
            grid[row] = grid[row].Replace('x', 'O');
        }
    }
  
  
    // Complete the bomberMan function below.
    static string[] bomberMan(int n, string[] grid) {
        if (n % 2 == 0)
            return plantBombAll(grid); 
  
        else {
            if (n == 1)
            {
                return grid; 
            }
            else if (n % 4 == 3)
            {
                detonateBomb(grid);
            }
            else if (n % 4 == 1)
            {
                detonateBomb(grid);
                detonateBomb(grid);
            }
        }
        return grid;
    }
  

Learning…

• c#의 경우, string의 N번째 index를 가져오려면 char[] 혹은 stringbuilder를 활용해야하는 것을 배웠다.
  • 링크

Reference

• HackerRank