hdu-1874

只是为了熟悉一下最短路径代码打的，这个题目是dijkstra算法的模版代码。我先看懂意思，然后自己敲了。

#include <cstdio>
#include <iostream>
#include <cstring>
#include <queue>
#include <algorithm>
using namespace std;

const int maxn = 210;
const int maxm = 2010;
typedef pair<int,int> pii;
int v[maxm],next[maxm],w[maxm];
int first[maxn],d[maxn],e;

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

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

void dij(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()){
        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(){
    int n,m,s,t,a,b,c;
    while(cin >> n >> m)
    {
        init();
        for(int i = 0;i < m;i++){
         cin >> a >> b >> c;
            add_edge(a,b,c);
            add_edge(b,a,c);
        }
        cin >> s >> t;
        dij(s);
      cout << d[t] << endl;
    }
    return 0;
}