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| #include <iostream>
#include <queue>
#define INF 0x3f3f3f3f
#define MAXN 3000
using namespace std;
struct Node
{
struct Edge *edge;
int dist;
int id;
Node()
{
edge = NULL;
dist = INF;
}
const bool operator <(const Node &tmp) const
{
return this->dist < tmp.dist;
}
}node[MAXN];
struct Edge
{
Node *from, *to;
Edge *next;
int val;
Edge(Node *from, Node *to, int val):
from(from), to(to), next(from->edge), val(val) {}
};
int dist[MAXN];
priority_queue<Node> q;
void Dijkstra(Node st)
{
dist[st.id] = 0;
st.dist = 0;
q.push(st);
while (!q.empty())
{
Node tmp = q.top();
q.pop();
if (dist[tmp.id]!=tmp.dist)
continue;
for (Edge *e = tmp.edge; e; e = e->next)
{
if ( dist[e->to->id] > tmp.dist + e->val)
{
Node to = *e->to;
dist[to.id] = tmp.dist + e->val;
to.dist = dist[to.id];
q.push( to );
}
}
}
}
int main()
{
int t, c, ts, te;
cin >> t >> c >> ts >> te;
for (int i = 1; i<=t; i++)
{
dist[i] = INF;
node[i].id = i;
}
for (int i = 0; i<c; i++)
{
int x, y, z;
cin >> x >> y >> z;
node[x].edge = new Edge(&node[x], &node[y], z);
node[y].edge = new Edge(&node[y], &node[x], z);
}
Dijkstra(node[ts]);
cout << dist[ node[te].id ];
}
|