Question

361. Bomb Enemy

中文文档

Description

Given an m x n matrix grid where each cell is either a wall 'W', an enemy 'E' or empty '0', return _the maximum enemies you can kill using one bomb_. You can only place the bomb in an empty cell.

The bomb kills all the enemies in the same row and column from the planted point until it hits the wall since it is too strong to be destroyed.

 

Example 1:

Input: grid = [["0","E","0","0"],["E","0","W","E"],["0","E","0","0"]]
Output: 3

Example 2:

Input: grid = [["W","W","W"],["0","0","0"],["E","E","E"]]
Output: 1

 

Constraints:

• m == grid.length
• n == grid[i].length
• 1 <= m, n <= 500
• grid[i][j] is either 'W', 'E', or '0'.

Solutions

Solution 1

class Solution:
  def maxKilledEnemies(self, grid: List[List[str]]) -> int:
    m, n = len(grid), len(grid[0])
    g = [[0] * n for _ in range(m)]
    for i in range(m):
      t = 0
      for j in range(n):
        if grid[i][j] == 'W':
          t = 0
        elif grid[i][j] == 'E':
          t += 1
        g[i][j] += t
      t = 0
      for j in range(n - 1, -1, -1):
        if grid[i][j] == 'W':
          t = 0
        elif grid[i][j] == 'E':
          t += 1
        g[i][j] += t
    for j in range(n):
      t = 0
      for i in range(m):
        if grid[i][j] == 'W':
          t = 0
        elif grid[i][j] == 'E':
          t += 1
        g[i][j] += t
      t = 0
      for i in range(m - 1, -1, -1):
        if grid[i][j] == 'W':
          t = 0
        elif grid[i][j] == 'E':
          t += 1
        g[i][j] += t
    return max(
      [g[i][j] for i in range(m) for j in range(n) if grid[i][j] == '0'],
      default=0,
    )

class Solution {
  public int maxKilledEnemies(char[][] grid) {
    int m = grid.length;
    int n = grid[0].length;
    int[][] g = new int[m][n];
    for (int i = 0; i < m; ++i) {
      int t = 0;
      for (int j = 0; j < n; ++j) {
        if (grid[i][j] == 'W') {
          t = 0;
        } else if (grid[i][j] == 'E') {
          ++t;
        }
        g[i][j] += t;
      }
      t = 0;
      for (int j = n - 1; j >= 0; --j) {
        if (grid[i][j] == 'W') {
          t = 0;
        } else if (grid[i][j] == 'E') {
          ++t;
        }
        g[i][j] += t;
      }
    }
    for (int j = 0; j < n; ++j) {
      int t = 0;
      for (int i = 0; i < m; ++i) {
        if (grid[i][j] == 'W') {
          t = 0;
        } else if (grid[i][j] == 'E') {
          ++t;
        }
        g[i][j] += t;
      }
      t = 0;
      for (int i = m - 1; i >= 0; --i) {
        if (grid[i][j] == 'W') {
          t = 0;
        } else if (grid[i][j] == 'E') {
          ++t;
        }
        g[i][j] += t;
      }
    }
    int ans = 0;
    for (int i = 0; i < m; ++i) {
      for (int j = 0; j < n; ++j) {
        if (grid[i][j] == '0') {
          ans = Math.max(ans, g[i][j]);
        }
      }
    }
    return ans;
  }
}

class Solution {
public:
  int maxKilledEnemies(vector<vector<char>>& grid) {
    int m = grid.size(), n = grid[0].size();
    vector<vector<int>> g(m, vector<int>(n));
    for (int i = 0; i < m; ++i) {
      int t = 0;
      for (int j = 0; j < n; ++j) {
        if (grid[i][j] == 'W')
          t = 0;
        else if (grid[i][j] == 'E')
          ++t;
        g[i][j] += t;
      }
      t = 0;
      for (int j = n - 1; j >= 0; --j) {
        if (grid[i][j] == 'W')
          t = 0;
        else if (grid[i][j] == 'E')
          ++t;
        g[i][j] += t;
      }
    }
    for (int j = 0; j < n; ++j) {
      int t = 0;
      for (int i = 0; i < m; ++i) {
        if (grid[i][j] == 'W')
          t = 0;
        else if (grid[i][j] == 'E')
          ++t;
        g[i][j] += t;
      }
      t = 0;
      for (int i = m - 1; i >= 0; --i) {
        if (grid[i][j] == 'W')
          t = 0;
        else if (grid[i][j] == 'E')
          ++t;
        g[i][j] += t;
      }
    }
    int ans = 0;
    for (int i = 0; i < m; ++i) {
      for (int j = 0; j < n; ++j) {
        if (grid[i][j] == '0') ans = max(ans, g[i][j]);
      }
    }
    return ans;
  }
};

func maxKilledEnemies(grid [][]byte) int {
  m, n := len(grid), len(grid[0])
  g := make([][]int, m)
  for i := range g {
    g[i] = make([]int, n)
  }
  for i := 0; i < m; i++ {
    t := 0
    for j := 0; j < n; j++ {
      if grid[i][j] == 'W' {
        t = 0
      } else if grid[i][j] == 'E' {
        t++
      }
      g[i][j] += t
    }
    t = 0
    for j := n - 1; j >= 0; j-- {
      if grid[i][j] == 'W' {
        t = 0
      } else if grid[i][j] == 'E' {
        t++
      }
      g[i][j] += t
    }
  }
  for j := 0; j < n; j++ {
    t := 0
    for i := 0; i < m; i++ {
      if grid[i][j] == 'W' {
        t = 0
      } else if grid[i][j] == 'E' {
        t++
      }
      g[i][j] += t
    }
    t = 0
    for i := m - 1; i >= 0; i-- {
      if grid[i][j] == 'W' {
        t = 0
      } else if grid[i][j] == 'E' {
        t++
      }
      g[i][j] += t
    }
  }
  ans := 0
  for i, row := range grid {
    for j, v := range row {
      if v == '0' && ans < g[i][j] {
        ans = g[i][j]
      }
    }
  }
  return ans
}