Plant a bomb at an empty cell. Go down and up, then right and left until there's a wall, and count enemies.

```
public class Solution {
public int maxKilledEnemies(char[][] grid) {
int max = 0;
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[0].length; j++) {
if (grid[i][j] == '0') {
max = Math.max(max, bomb(grid, i, j));
}
}
}
return max;
}
private int bomb(char[][] grid, int row, int col) {
int dead = 0;
for (int i = row + 1; i < grid.length && grid[i][col] != 'W'; i++)
if (grid[i][col] == 'E') dead++;
for (int i = row - 1; i >= 0 && grid[i][col] != 'W'; i--)
if (grid[i][col] == 'E') dead++;
for (int j = col + 1; j < grid[0].length && grid[row][j] != 'W'; j++)
if (grid[row][j] == 'E') dead++;
for (int j = col - 1; j >= 0 && grid[row][j] != 'W'; j--)
if (grid[row][j] == 'E') dead++;
return dead;
}
}
```