bzoj1579 [Usaco2009 Feb]Revamping Trails 道路升级

#include<bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 5, maxm = 3e5 + 5;
struct lpl{
    int to, dis;
}lin;
struct ld{
    int num, dis;
    bool operator < (const ld &A)const{
        return A.dis < dis;
    }
}qwe, lpd;
vector<lpl> point[maxn];
int n, m, k, s, t;
int a[maxm], b[maxm], c[maxm], dis[maxm];
bool vis[maxn];

inline void putit()
{
    int x, y; scanf("%d%d%d", &n, &m, &k); k++;
    for(int i = 1; i <= m; ++i) scanf("%d%d%d", &a[i], &b[i], &c[i]);
}

inline void connect(int u, int v, int dis)
{
    lin.dis = dis;
    lin.to = v; point[u].push_back(lin);
}

inline void build()
{
    for(int i = 1; i <= k; ++i) 
        for(int j = 1; j <= m; ++j){
            connect(a[j] + (i - 1) * n, b[j] + (i - 1) * n, c[j]);
            connect(b[j] + (i - 1) * n, a[j] + (i - 1) * n, c[j]);          
        }
    for(int i = 1; i < k; ++i) 
        for(int j = 1; j <= m; ++j)
            connect(a[j] + (i - 1) * n, b[j] + i * n, 0), connect(b[j] + (i - 1) * n, a[j] + i * n, 0);
    for(int i = 1; i <= n; ++i)
        for(int j = 1; j < k; ++j)
            connect((j - 1) * n + i, j * n + i, 0);
}

inline void dijkstra()
{
    s = 1, t = n * k;
    priority_queue<ld> q;
    memset(dis, 0x3f, sizeof(dis));
    qwe.num = s, qwe.dis = 0;
    q.push(qwe); dis[s] = 0;
    while(!q.empty()){
        qwe = q.top(); q.pop();
        if(vis[qwe.num]) continue;
        vis[qwe.num] = true;
        for(int i = point[qwe.num].size() - 1; i >= 0; --i){
            int now = point[qwe.num][i].to;
            if(vis[now]) continue;
            if(dis[now] > dis[qwe.num] + point[qwe.num][i].dis){
                dis[now] = dis[qwe.num] + point[qwe.num][i].dis;
                lpd.num = now, lpd.dis = dis[now];
                q.push(lpd);
            }
        }
    }
}

int main()
{
    putit();
    build();
    dijkstra();
    cout << dis[t];
    return 0;
}