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| class Solution {
public:
vector<vector<int>> vis;
int rows;
int cols;
int result;
int* rdir;
int* cdir;
void DFS(vector<vector<char>>& grid, int r, int c)
{
if (vis[r][c]) return;
if (grid[r][c] == '1')
{
vis[r][c] = true;
for(int k = 0; k < 4; ++k)
{
int i = r + rdir[k];
int j = c + cdir[k];
if(i >=0 && i < rows && j >= 0 && j < cols && vis[i][j] == 0)
DFS(grid,i,j);
}
}
}
int numIslands(vector<vector<char>>& grid) {
result = 0;
rows = grid.size();
if (rows == 0) return 0;
cols = grid[0].size();
if (cols == 0) return 0;
vis = vector<vector<int>>(rows,vector<int>(cols,0));
int rdirs[] = {0,0,1,-1};
int cdirs[] = {1,-1,0,0};
rdir = rdirs;
cdir = cdirs;
for (int i = 0; i < rows; ++i)
{
for (int j = 0; j < cols; ++j)
{
if (vis[i][j] == 0 && grid[i][j] == '1')
{
++result;
DFS(grid,i,j);
}
}
}
return result;
}
};
|