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Shortest Path in Weighted Graph : (Using Dijkstra)
#include<bits/stdc++.h>
using namespace std;
vector<int>d;
vector< vector< pair<int,int> > >graph;
vector<bool>mark;
void dijkstra(int s,int n){
int u,i;
d[s]=0;
pair<int,int>p;
set< pair<int,int> >st;
for(int i=1;i<=n;i++)
st.insert(make_pair(d[i],i));
while(!st.empty()){
u=st.begin()->second;
mark[u]=true;
st.erase(st.begin());
for(i=0;i<graph[u].size();i++){
p=graph[u][i];
if(d[u]+p.second<d[p.first] && mark[p.first]==false){
st.erase(make_pair(d[p.first],p.first));
d[p.first]=d[u]+p.second;
st.insert(make_pair(d[p.first],p.first));
}
}
}
}
int main()
{
int n,m,u,v,w,i,t,j,a,b;
cout<<"Enter the no of vertices..";
cin>>n;
mark.resize(n+1);
graph.resize(n+1);
d.resize(n+1);
cout<<"\nEnter the number of edges...";
cin>>m;
cout<<"\nEnter the edges along with their weights...\n";
for(i=1;i<=m;i++){
cin>>u>>v>>w;
graph[u].push_back(make_pair(v,w));
graph[v].push_back(make_pair(u,w));
}
// Calculating the single source shortest paths...
fill_n(mark.begin(),n+1,false);
fill_n(d.begin(),n+1,INT_MAX);
cout<<"\nEnter the source and destination...";
cin>>u>>v;
dijkstra(u,n);
cout<<"\nThe Shortest distance is..."<<d[v]<<endl;
return 0;
}
@okarim4259

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okarim4259 commented Apr 14, 2018

Hi would you happen to know how to print the shortest path from this algorithm?

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