/
uva10356.cpp
executable file
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/
uva10356.cpp
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#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0), cout.precision(15);
#define UNVISITED -1
using namespace std;
typedef long long int64;
typedef pair<int, int> ii;
typedef tuple<int, int, int> iii;
#define walk 0
#define ride 1
int n, r;
vector< vector<int> > dist;
vector< vector< ii > > AdjList;
priority_queue< iii, vector< iii >, greater< iii > > pq;
void dijkstra(){
int u, v, d1, d2, currStatus;
u = 0, d1 = 0, currStatus = walk;
dist[currStatus][0] = 0;
pq.push(iii(dist[currStatus][0], 0, currStatus));
while(!pq.empty()){
tie(d1, u, currStatus) = pq.top(); pq.pop();
if(d1 > dist[currStatus][u]) continue;
for(int i = 0; i < AdjList[u].size(); ++i){
v = AdjList[u][i].first, d2 = AdjList[u][i].second;
if(d1 + d2 < dist[1 - currStatus][v]){
dist[1 - currStatus][v] = d1 + d2;
pq.push(iii(dist[1 - currStatus][v], v, 1 - currStatus));
}
}
}
}
int main(){ _
int tc = 0;
while(cin >> n >> r){
dist.assign(2, vector<int> (n, INT_MAX));
AdjList.assign(n, vector< ii > (0));
int u, v, w;
for(int i = 0; i < r; ++i){
cin >> u >> v >> w;
AdjList[u].push_back(ii(v, w));
AdjList[v].push_back(ii(u, w));
}
dijkstra();
cout << "Set #" << ++tc << endl;
if(dist[walk][n-1] == INT_MAX) cout << "?" << endl;
else cout << dist[walk][n-1] << endl;
}
return 0;
}