Re: Iterate over the adjacent elements in a matix container

"Paul" <pchristor@yahoo.co.uk> wrote in message
news:j68oip$r0u$1@adenine.netfront.net...


<snip>

And here's an example using recursion, its very similar. Again the
complexity seems to be in the getAdjacents function. It appears to be
simpler but there is more data stored on the stack as someone else has
already explained. I am still to understand this "breath first" method
Richard was talking about or the "seed method" Krice mentioned. I will
think more about this to try and find a better way.

/*Code. again very rough but just an example.*/
#include <iostream>
#include<vector>

std::vector<int> getAdjacents(int index, int rows=7, int cols=8){
 std::vector<int> ret;
 if( (index/cols==(index-1)/cols)&& index!=0 ) ret.push_back(index-1);
 if((index+1)%cols) ret.push_back(index+1);
 if(index-cols>=0) ret.push_back(index-cols);
 if( (index+cols)<(rows*cols)) ret.push_back(index+cols);
 return ret;
}

void recurse(std::vector<int>& v, int i, int initval, int newval){
 std::vector<int> adjacents=getAdjacents(i);
 for(int i=0; i<adjacents.size(); ++i){
  if(v[adjacents[i]]==initval){
   v[adjacents[i]]= newval;
   recurse(v, adjacents[i], initval, newval);
  }
 }
}

void clickme(std::vector<int>& v, int clicked=55, int newval=4){
 int initval= v[clicked];
 v[clicked]=newval;
 recurse(v, clicked, initval, newval);
}

int main(){
 std::vector<int> v(56,2);
 v[5]=3;
 v[13]=3;
 v[21]=3;
 v[22]=3;
 v[23]=3;
 std::cout<<"Before clickme:";
 for(int i=0; i<v.size(); ++i){
  if(i%8==0) std::cout<<std::endl;
  std::cout<< v[i];
 }
 clickme(v);
 std::cout<<"\n\nAfter clickme:";
 for(int i=0; i<v.size(); ++i){
  if(i%8==0) std::cout<<std::endl;
  std::cout<< v[i];
 }
}

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