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class Solution {
public:
    void dfs(int i, int j, vector<vector<char>>& grid, vector<vector<bool>>& vis) {
        if(i<0 || i>=grid.size() || j<0 || j>=grid[0].size() || vis[i][j] || grid[i][j]=='0') return;
        vis[i][j] = true;
        dfs(i-1,j,grid,vis);
        dfs(i+1,j,grid,vis);
        dfs(i,j-1,grid,vis);
        dfs(i,j+1,grid,vis);
    }

    int numIslands(vector<vector<char>>& grid) {
        int count = 0;
        vector<vector<bool>> vis(grid.size(), vector<bool>(grid[0].size(), false));
        for(int i=0; i<grid.size(); i++){
            for(int j=0; j<grid[0].size(); j++){
                if(grid[i][j]=='1' && !vis[i][j]){
                    dfs(i,j,grid,vis);
                    count++;
                }
            }
        }
        return count;
    }
};