Bomb Enemy (atten)

1. idea

public class Solution {
    public int maxKilledEnemies(char[][] grid) {
        if(grid.length == 0 || grid[0].length == 0){
            return 0;
        }
        int maxNum = 0;
        int[] rowHits = new int[grid.length], colHits = new int[grid[0].length];
        for (int i=0; i<grid.length; ++i){
            for (int j=0; j<grid[0].length; ++j){
                if(i==0 || grid[i-1][j] == 'W'){
                    colHits[j] = 0;
                    for (int k=i; k<grid.length; ++k){
                        if(grid[k][j] == 'W'){
                            break;
                        } else if(grid[k][j] == 'E'){
                            ++colHits[j];
                        }
                    }
                }
                if (j == 0 || grid[i][j-1] == 'W'){
                    rowHits[i] = 0;
                    for (int k=j; k<grid[0].length; ++k){
                        if(grid[i][k] == 'W'){
                            break;
                        } else if (grid[i][k] == 'E'){
                            ++rowHits[i];
                        }
                    }
                }
                if (grid[i][j] == '0'){
                    maxNum = Math.max(maxNum, colHits[j] + rowHits[i]);
                }
            }
        }
        return maxNum;
    }
}