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#include <iostream>
#include <fstream>
#include <string>
#include <queue>
#include <vector>
#include <iterator>
using namespace std;
struct Edge
{
int end; //this is the node that the edge points to.
int weight; //this is the weight of the node, very important!
int origin; //finally, this is the node which we are pointing to, just in case it's needed.
Edge(int start, int dest, int lbs): origin(start), end(dest), weight(lbs){ };
bool operator < (const Edge& a) const
{
return weight < a.weight;
}
};
const int INFINITY = 76543210;
int filelength(string filename)
{
ifstream file;
string str;
int lines=0;
file.open(filename);
while (getline(file, str))
{
lines++;
}
file.close();
return lines;
}
void dij(int x, const vector<vector<Edge>> &list, vector<int> &path, vector<int> &visited)
{
priority_queue<Edge> Q;
int a = list.size();
Edge origin = Edge(list[x][0].origin, list[x][0].end, list[x][0].weight);
//origin.origin = x;
path.clear(); //clean out any pre-existing junk
path.resize(a, INFINITY);
visited.resize(a, -1);
Q.push(origin);
path.clear();
path.assign(a, INFINITY);
//cout<<path[0];
//path.assign(a, 0);
while (!Q.empty())
{
Edge temp = Edge(Q.top().origin, Q.top().end, Q.top().weight);//we need to preserve the top value so we can use it later
Q.pop();//removing the top
//cout<<"eee";
int begin = temp.origin;
for(std::size_t i=0;i < list[begin].size()-1;++i )
{
//cout<<"fff";
//cout<<list[begin].size();
if(list[begin][i].weight != 0)
{
//cout<<path[begin];
//cout<<"ggg";
//cout<<i<<" "<<begin;
//cout<<path[i];
if(path[i] < (path[begin] + list[begin][i].weight))
{
// cout<<"hhh";
path[i] = path[begin] + list[begin][i].weight;
}
// cout<<"iii";
if(!visited[i])
{
Edge newEdge(list[begin][i].origin, list[begin][i].end, path[i]);
Q.push(newEdge);
visited[i] = true;
}
//cout<<"hhh";
}
}
}//closure of the while loop
cout << "The shortest distance from " << x << " to all the nodes is" << endl;
for(int i=0;i < list.size()-1;i++ )
{
cout << i << " : " << path[i] << endl;
}
cout << endl << endl;
}
int main()
{
//Edge original;
//original.weight = 0;
vector<vector<Edge>> list;
vector<int> path;
vector<int> visited;
std::vector<int>::size_type sz = path.size();
int e = 0; //This is the total size of the vector. It gets determined once
string filename;
printf("Enter the name of the file: ");
cin>>filename;
ifstream infile;
infile.open(filename);
int v = 0;
int x;
//cout<<filename;
if(!infile.is_open())
{
cout << "Error opening file";
//cin.get();
exit(EXIT_FAILURE);
}
infile>>x;
Edge original(x, x, 0);
original.origin = original.end;
e = filelength(filename);
list.resize(e);
int a,b/*,c*/;
//c=0;
while(infile>>v>>a>>b)
{
list[v].push_back(Edge(v,a,b));
}
//the first is the origin point, the second is the n-1th term. for example 00 is the first listed value of the node 0
//cout<<list[0][0].weight;
for (unsigned i=0; i<sz; i++)
{
path[i]=i;
}
infile.close();
dij(x, list, path, visited);
cin>>x;
//quit();
return 0;
}
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