SDE GRAPH NO of Islands

 class Solution {

public:

void DFS(int r,int c,vector<vector<char>>&grid,int n,int m,vector<vector<int>>&visited,int color){

int rn[]={0,0,1,-1};

int cn[]={-1,1,0,0};

visited[r][c]=color;

for(int i=0;i<4;i++){

int rnxt=r+rn[i];

int cnxt=c+cn[i];

if(rnxt>=0&&rnxt<n&&cnxt>=0&&cnxt<m)if(!visited[rnxt][cnxt]&&grid[rnxt][cnxt]=='1')DFS(rnxt,cnxt,grid,n,m,visited,color);

//if(cnxt>=0&&cnxt<m)if(!visited[rnxt][cnxt])DFS(rnxt,cnxt,grid,n,m,visited);

}

}

int numIslands(vector<vector<char>>& grid) {

int n=grid.size();

int m=grid[0].size();

vector<vector<int>>visited(n,vector<int>(m,0));

int color=1;

for(int i=0;i<n;i++){

for(int j=0;j<grid[i].size();j++){

if(!visited[i][j]&&grid[i][j]=='1'){

DFS(i,j,grid,n,m,visited,color);

color++;

}

}

}

return color-1;

}

};