Dij_heap__前向星。

//前向星
struct node {
    int nxt;
    int val;
    int lst;
    node () {}
    node (int next, int value) : nxt(next), val(value) {}
};

struct headnode {
    int u;
    int val;
    headnode () {}
    headnode (int uu, int value) : u(uu), val(value) {}
    bool operator < (const headnode &a) const {
        return val > a.val;
    }
};  // 用于优先队列而已。val是比较的值。dist[i]

int dist[maxn];
bool vis[maxn];

node edge[maxn];
int  last[maxn]

void Dij()
{
    memset(dist, 0x3f, sizeof(dist));
    memset(vis,  0,    sizeof(vis));
    priority_queue<headnode> pq;
    pq.push(headnode(1, 0));
    dist[1] = 0;
    headnode now;
    while (!pq.empty()) {
        now = pq.top(); pq.pop();
        if (vis[now.u]) continue;
        vis[now.u] = true;
        for (int i=last[now.u]; i!=-1; i=edge[i].lst) {
            if (dist[edge[i].nxt] > edge[i].val + dist[now.u]) {
                dist[edge[i].nxt] = edge[i].val + dist[now.u];
                pq.push(headnode(edge[i].nxt, dist[edge[i].nxt]));
            }    
        }
    }
}