Leetcode 419. Battleships in a Board

class Solution {
public int countBattleships(char[][] board) {
if(board.length == 0 || board[0].length == 0){
return 0;
}
int ans = 0;
if(board[0][0] == 'X'){
ans++;
}
for(int i = 1; i < board.length; i++){
if(board[i][0] == 'X' && board[i - 1][0] != 'X'){
ans++;
}
}
for(int i = 1; i < board[0].length; i++){
if(board[0][i] == 'X' && board[0][i - 1] != 'X'){
ans++;
}
}
for(int i = 1; i < board.length; i++){
for(int j = 1; j < board[0].length; j++){
if(board[i][j] == 'X' && board[i - 1][j] != 'X' && board[i][j - 1] != 'X'){
ans++;
}
}
}
return ans;
}
}