419. 棋盘上的战舰

简单

class Solution {
public:int countBattleships(vector<vector<char>>& board) {int ans = 0;for(int i=0;i<board.size();++i){for(int j=0;j<board[0].size();++j){if(board[i][j] == 'X'){dfs(board,i,j);++ans;}}}return ans;}void dfs(vector<vector<char>> &board,int x,int y){board[x][y] = 'a';int dx[4] = {1,0,-1,0};int dy[4] = {0,1,0,-1};for(int i = 0;i<4;++i){int nx = dx[i] + x;int ny = dy[i] + y;if(nx>=0 && nx < board.size() && ny >= 0 && ny < board[0].size() && board[nx][ny] == 'X'){dfs(board,nx,ny);}}}
};