# DFS C++

• class Solution {
public:
void dfs(vector<vector<char>>& board, int i, int j)
{
visited[i][j] = true;
//left
if (i >= 0 && i < n && j - 1 >= 0 && j - 1 < m && !visited[i][j - 1] && board[i][j - 1] == 'X')
{
dfs(board, i, j - 1);
}
//right
if (i >= 0 && i < n && j + 1 >= 0 && j + 1 < m && !visited[i][j + 1] && board[i][j + 1] == 'X')
{
dfs(board, i, j + 1);
}
//top
if (i - 1 >= 0 && i - 1 < n && j >= 0 && j < m && !visited[i - 1][j] && board[i - 1][j] == 'X')
{
dfs(board, i - 1, j);
}
//bottom
if (i + 1 >= 0 && i + 1 < n && j >= 0 && j < m && !visited[i + 1][j] && board[i + 1][j] == 'X')
{
dfs(board, i + 1, j);
}
}

``````int countBattleships(vector<vector<char>>& board) {
n = board.size();
m = board[0].size();
num = 0;
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < m; ++j)
{
visited[i][j] = false;
}
}
for (int i = 0; i < n; ++i)
{
for (int j = 0; j < m; ++j)
{
if (board[i][j] == 'X' && !visited[i][j])
{
num++;
dfs(board, i, j);
}
}
}
return num;
}
``````

private:
int n;
int m;
int num;
bool visited[1000][1000];
};

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