Modifying data of custom data structure - c++

Question

I have an input file that I'm trying to parse in order to perform operations like DFS, Best-First Search, A* search, etc.
It looks like this:
| The vertical bar denotes comments. Ignore.
|
| The first non-comment line contains N, the number of nodes in the graph.
5
| The second non-comment line contains the unique start node.
0
| The third non-comment line contains a single goal node.
3
| The fourth non-comment line specifies the number of heuristics.
1
| The fifth non-comment line starts the edge-cost adjacency matrix. [i,j] in the matrix represents the weight of the edge from node i to node j.
* 1 2 * *
* * 3 * *
* * * 5 4
* * * * *
* * * * *
| After the adjacency matrix, the heuristic evaluation vectors are given,
| where each row containing the heuristic value h(n) for a node n
3
6
1
0
For the code, I created a class for the nodes in the Adjacency list and a class for the graph. I have managed to parse all the input except the last one, the heuristic evaluation numbers. Here is my code:
class AdjListNode
{
private:
int v; // vertex or node number.
int weight; // weight on edge to reach a particular vertex.
int h; // a heuristic number for every node.
public:
AdjListNode(int _v, int _w) { v = _v; weight = _w;}
int getV() { return v;} // return the vertex number
int getWeight() {return weight;}
void setH(int _h) { h = _h;}
int getH() { return h;}
};
class Graph
{
private:
int V; // Total number of nodes/vertices in the graph
list<AdjListNode> *adj; // a list for storing all the nodes
//A helper function for Depth-First Search DFS.
bool DFSUtil(int v, bool visited[], int goal, int cost);
public:
Graph(int V);
void DFS(int v, int goal); // Depth First Search
void addEdge(int i, int j, char* val); // Add edge between i and j
// of weight val.
//Print the adjacency list;
void printList();
};
void Graph::printList()
{
list<AdjListNode>::iterator i;
for (int j = 0; j < V; j++)
{
for (i = adj[j].begin(); i != adj[j].end(); i++)
{
AdjListNode node = *i;
cout << node.getV() << " ";
}
cout << endl;
}
}
Graph::Graph(int V)
{
this->V = V;
adj = new list<AdjListNode>[V];
}
void Graph::addEdge(int u, int v, char* val)
{
int weight = atoi(val);
AdjListNode node(v, weight);
adj[u].push_back(node);
}
bool Graph::DFSUtil(int v, bool visited[], int goal, int cost)
{
visited[v] = true;
if (v == goal)
{
cout << "cost is : " << cost << endl;
cout << "path is : ";
return true;
}
list<AdjListNode>:: iterator i;
for (i = adj[v].begin(); i != adj[v].end(); i++)
{
AdjListNode node = *i;
if (!visited[node.getV()])
{
if (DFSUtil(node.getV(), visited, goal, cost + node.getWeight()))
{
cout << node.getV() << " " ;
return true;
}
}
}
return false;
}
void Graph::DFS(int v, int goal)
{
bool *visited = new bool[V];
for (int i = 0; i < V; i++)
visited[i] = false;
int cost = 0;
DFSUtil(v, visited, goal, cost);
}
Here is the main() function where I am trying to parse all the values from the input file:
int main()
{
string line; // read every line into this variable
int argCount = 0; // keep track of 4 arguments (V, start, goal, and
// J)
int V, start, goal, J; // V is number of nodes, start is the start
// node, goal is goal node, J is just a
// number (ignore for now)
//input for nodes, start, goal, and J
while (getline(cin, line) && argCount < 4)
{
if (line[0] == '|') // reject the line and continue if the line
continue; // starts with '|'
// convert the line which is a string into int and store in
// respective variables
switch (argCount)
{
case 0: V = stoi(line);
argCount++;
break;
case 1: start = stoi(line);
argCount++;
break;
case 2: goal = stoi(line);
argCount++;
break;
case 3: J = stoi(line);
argCount++;
break;
}
}
Graph g(V); // create a Graph of 'V' nodes or vertices.
//ignore lines starting with '|'
while (getline(cin, line))
{
if (line[0] == '|')
continue;
break;
}
// after the above loop, line contains the first row of the matrix
// buffer array for taking in weight from stringstream.
char weight[100];
//parse first row of the matrix
stringstream ss;
ss << line;
for (int v = 0; v < V; v++)
{
ss.getline(weight, 6, ' '); // get the value into weight,
// ' '(whitespace) is a delimiter.
if (weight[0] != '*') // ignore if weight is '*'
g.addEdge(0, v, weight);// call addEdge() to add edge
// between 0 (because this is the
// first row) and v and assign
// weight.
}
ss << ""; // reset stringstream.
ss.clear();
// parse rest of the rows of the matrix. first row already parsed
// above
for (int u = 1; u < V; u++) // u is row, starting from 1.
{ getline(cin, line); // take the whole line
ss.clear();
ss.str("");
ss << line; // put the line in stringstream
int v = 0; // v is column number.
while (ss >> weight)
{
if (weight[0] != '*')
g.addEdge(u, v, weight); // add Edge between u and v.
v++; // increment column number.
}
}
//ignore lines starting with '|' else set the h value for the nodes
// THIS IS WHERE I AM STUCK. I NEED TO TAKE IN THE H VALUES AND
// ASSOCIATE THEM WITH THEIR NODES WHICH ARE ALREADY CREATED.
int n = 0;
list<AdjListNode>::iterator i;
while (getline(cin, line))
{
//cout << line;
if (line[0] == '|')
continue;
int h = stoi(line);
}
cout << "The adjacency list is : " << endl;
g.printList();
g.DFS(start, goal);
cout << endl;
return 0;
}
How can I take in the h values and associate them with the correct nodes? I am confused because I am calling the addEdge() function to add the edges between the nodes before taking in the h values. I tried to use getters and setters but I am not able to implement those concepts because I am a novice.
Thanks!
EDIT 1 : Added comments.
EDIT 2 : The class structure is supposed to be this:
For the adjacency list node class, AdjListNode:
Each node has 3 attributes; an integer v to identify it, a weight for calculating the cost to reach that node, and a heuristic value h which I am confused on how to assign because I have already called the constructor and would be parsing the h values from the input file later.
I know I am missing some elementary concept here.
For the class Graph:
A list stores all the AdjListNode type nodes as an adjacency list. I need to perform A* search on this.

Answer 1

EDIT: The core of your difficulty here is found in your class structure. Think about your goal - you want to associate an h with an edge, correct? The word "associate" means that you need some sort of data structure in your class(es) that allows you to do just that.
There are a few structures to choose from: tuples and structs are two possibilities. If you store the structure in your list, you can enter all of edges, and then step through and enter all of the h values.
Another possibility is to use a union to allow you to store both types of values in the same list. This will be more difficult, but may accomplish your goal.
Beyond this, you will need to do the research yourself, here.
--
I know you're new here, so I'll let you know that very few people will just give you the correct code outright, especially on something this complex. Just a heads up.
Second, you're on rather shaky ground if you do not understand your own object structure. I'm having a hard time reading it myself, and I'm a professional. Please, for the love of all things digital, comment your code! What do your various one- or two-letter variables mean...or the ones with the longer but still elusive names? (Don't feel too bad about this...common habit among programmers. Ask anyone here.)
Getters and setters are not a complex matter. Getters simply return the value of a private variable in the class. A setter is a function that accepts an argument, and assigns that argument to a particular private variable in the class, usually after checking for errors.
The best advice I can give you right now is A) comment your code, and B) figure out your code's basic object structure. Literally write (on paper if you have to) the names of your objects, what is stored inside them, what's hidden and what's public, and what they're supposed to do. If you figure that out, you'll probably find your answer on your own. Otherwise, edit your question with that information.
If I see that work - the intended class structure and some good comments - I'll edit with more details on how to fix your code. It's about doing the footwork yourself.
By the way, you have variables hanging out above your scope declarations (in this case, public:) in your headers, which is a no-no.