Recently (4 days) I started learning C ++ based on the background of C / Java. To learn a new language, I begin by reintegrating various classic algorithms as much as I can.
I came to this code, its DFS - Depth First Search in an undirected graph. However, from what I read, it is best to pass parameters via C ++ links. Unfortunately, I cannot fully understand the concept of a link. Every time I need a link, I get embarrassed and think in terms of pointers. In my current code, I use pass by value.
Here is the code (maybe not Cppthonic as it should):
#include <algorithm>
#include <iostream>
#include <fstream>
#include <string>
#include <stack>
#include <vector>
using namespace std;
template <class T>
void utilShow(T elem);
template <class T>
void utilShow(T elem){
cout << elem << " ";
}
vector< vector<short> > getMatrixFromFile(string fName);
void showMatrix(vector< vector<short> > mat);
vector<unsigned int> DFS(vector< vector<short> > mat);
vector< vector<short> > getMatrixFromFile(string fName)
{
unsigned int mDim;
ifstream in(fName.c_str());
in >> mDim;
vector< vector<short> > mat(mDim, vector<short>(mDim));
for(int i = 0; i < mDim; ++i) {
for(int j = 0; j < mDim; ++j) {
in >> mat[i][j];
}
}
return mat;
}
void showMatrix(vector< vector<short> > mat){
vector< vector<short> >::iterator row;
for(row = mat.begin(); row < mat.end(); ++row){
for_each((*row).begin(), (*row).end(), utilShow<short>);
cout << endl;
}
}
vector<unsigned int> DFS(vector< vector<short> > mat){
stack<unsigned int> nodeStack;
vector<bool> visited(mat.size(), false);
vector<unsigned int> result;
nodeStack.push(0);
visited[0] = true;
while(!nodeStack.empty()) {
unsigned int cIdx = nodeStack.top();
nodeStack.pop();
result.push_back(cIdx);
for(int i = 0; i < mat.size(); ++i) {
if(1 == mat[cIdx][i] && !visited[i]) {
nodeStack.push(i);
visited[i] = true;
}
}
}
return result;
}
int main()
{
vector< vector<short> > mat;
mat = getMatrixFromFile("Ex04.in");
vector<unsigned int> dfsResult = DFS(mat);
cout << "Adjancency Matrix: " << endl;
showMatrix(mat);
cout << endl << "DFS: " << endl;
for_each(dfsResult.begin(), dfsResult.end(), utilShow<unsigned int>);
return (0);
}
Could you give me some tips on how to use links when referencing this code?
Is my current programming style compatible with C ++ constructs?
** ++?
LATER EDIT:
, ( ), OOP. , . const, , NULL.
:
#include <algorithm>
#include <fstream>
#include <iostream>
#include <ostream>
#include <stack>
#include <string>
#include <vector>
using namespace std;
template <class T> void showUtil(T elem);
template <class T>
class SGraph
{
private:
size_t nodes;
vector<T> pmatrix;
public:
SGraph(): nodes(0), pmatrix(0) { }
SGraph(size_t nodes): nodes(nodes), pmatrix(nodes * nodes) { }
SGraph(string &file_name);
void resize(size_t new_size);
void print();
void DFS(vector<size_t> &results, size_t start_node);
T & operator()(size_t row, size_t col) {
return pmatrix[row * nodes + col];
}
};
template <class T>
SGraph<T>::SGraph(string &file_name)
{
ifstream in(file_name.c_str());
in >> nodes;
pmatrix = vector<T>(nodes * nodes);
for(int i = 0; i < nodes; ++i) {
for(int j = 0; j < nodes; ++j) {
in >> pmatrix[i*nodes+j];
}
}
}
template <class T>
void SGraph<T>::resize(size_t new_size)
{
this->pmatrix.resize(new_size * new_size);
}
template <class T>
void SGraph<T>::print()
{
for(int i = 0; i < nodes; ++i){
cout << pmatrix[i];
if(i % nodes == 0){
cout << endl;
}
}
}
template <class T>
void SGraph<T>::DFS(vector<size_t> &results, size_t start_node)
{
stack<size_t> nodeStack;
vector<bool> visited(nodes * nodes, 0);
nodeStack.push(start_node);
visited[start_node] = true;
while(!nodeStack.empty()){
size_t cIdx = nodeStack.top();
nodeStack.pop();
results.push_back(cIdx);
for(int i = 0; i < nodes; ++i){
if(pmatrix[nodes*cIdx + i] && !visited[i]){
nodeStack.push(i);
visited[i] = 1;
}
}
}
}
template <class T>
void showUtil(T elem){
cout << elem << " ";
}
int main(int argc, char *argv[])
{
string file_name = "Ex04.in";
vector<size_t> dfs_results;
SGraph<short> g(file_name);
g.DFS(dfs_results, 0);
for_each(dfs_results.begin(), dfs_results.end(), showUtil<size_t>);
return (0);
}