TLE in codeforces's Dijkstra - c++

Question

I just learnt Dijkstra's algorithm and solved a few problems and I am trying to solve this http://codeforces.com/problemset/problem/20/C problem but I am getting Time limit Exceeded in a large test case, I want to know if my code can be further optimized in any way or if there is any other faster implementation of Dijkstra then let me know.
My code
#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define vp vector<pii>
int p[100010],d[100010];
void printer(int current)
{
if(p[current]==-2)
{
printf("%d ",current);
return;
}
printer(p[current]);
printf("%d ",current);
}
class Prioritize
{
public:
int operator()(const pii &p1,const pii &p2)
{
return p1.second<p2.second;
}
};
int main()
{
priority_queue<pii, vp, Prioritize> Q;
int nv;
scanf("%d",&nv);
vp g[nv+1];
int ne,u,v,w;
scanf("%d",&ne);
for(int i=0;i<ne;i++)
{
scanf("%d %d %d",&u,&v,&w);
g[u].push_back(pii(v,w));
g[v].push_back(pii(u,w));
}
int source=1;
int size;
for(int i=1;i<=nv;i++)
{
d[i]=INT_MAX;
p[i]=-1;
}
d[source]=0;
p[source]=-2;//marker for source.
Q.push(pii(source,d[source]));
while(!Q.empty())
{
u=Q.top().first;
Q.pop();
size=g[u].size();
for(int i=0;i<size;i++)
{
v=g[u][i].first;
w=g[u][i].second;
if(d[v]>d[u]+w)
{
d[v]=d[u]+w;
p[v]=u;
Q.push(pii(v,d[v]));
}
}
}
/*for(int i=1;i<=nv;i++)
{
printf("Node %d and min weight = %d and parent = %d\n",i,d[i],p[i]);
}*/
if(p[nv]==-1)
{
printf("%d\n",-1);
return 0;
}
printer(nv);
return 0;
}

Answer 1

Your algorithm has complexity O(nm). I propose to add the following
Q.push(pii(source,d[source]));
while(!Q.empty())
{
u=Q.top().first;
int curD = Q.top().second; //this
if( curD > d[u]) continue; //and this
Q.pop();
size=g[u].size();
for(int i=0;i<size;i++)
{
After changes complexity will be O(mlogn). If you now russian you can read http://e-maxx.ru/algo/dijkstra_sparse