hdu2544

標準的dijkstra。

#include <iostream>
#include <memory.h>
#include <queue>
using namespace std;

int N,M;
int v[10002],next[10002],w[10002];
int first[102],d[102],e;
typedef pair<int,int> pii;

void init()
{
    e = 0;
    memset(first,-1,sizeof(first));
}

void add_edge(int a,int b,int c)
{
    v[e] = b;w[e] = c;
    next[e] = first[a];first[a] = e ++;
}

void dijkstra(int src)
{
    priority_queue<pii,vector<pii>,greater<pii> > q;
    memset(d,-1,sizeof(d));
    d[src] = 0;
    q.push(make_pair(0,src));
    while(!q.empty())
    {
        if(!q.empty() && q.top().first > d[q.top().second]) q.pop();
        if(q.empty()) break;
        int u = q.top().second;
        q.pop();
        for(int i = first[u];i != -1;i = next[i]){
            if(d[v[i]] == -1 || d[v[i]] > d[u] + w[i]){
                d[v[i]] = d[u] + w[i];
                q.push(make_pair(d[v[i]],v[i]));
            }
        }
    }
}

int main()
{
    while((cin >> N >> M) && N + M > 0){
        init();
        int a,b,c;
        for(int i = 0;i < M;i ++)
        {
            cin >> a >> b >> c;
            add_edge(a,b,c);
            add_edge(b,a,c);
        }
        dijkstra(1);
        cout << d[N] << endl;
    }
    return 0;
}