bzoj 1975: [Sdoi2010]魔法猪学院 [k短路]

1975: [Sdoi2010]魔法猪学院

裸题...

被double坑死了

#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <queue>

using namespace std;

typedef long long ll;

#define pdi pair<double, int>

#define fir first

#define sec second

const int N = 5005, M = 2e5+5;

inline int read(){

    char c=getchar(); int x=0,f=1;

    while(c<'0'||c>'9') {if(c=='-')f=-1;c=getchar();}

    while(c>='0'&&c<='9') {x=x*10+c-'0';c=getchar();}

    return x*f;

}

int n, m, u, v, s, t; double en, w;

namespace I {

    struct edge {int v, ne; double w;} e[M];

    int cnt, h[N];

    inline void ins(int u, int v, double w) {

        e[++cnt] = (edge){v, h[u], w}; h[u] = cnt;

    }

    priority_queue<pdi, vector<pdi>, greater<pdi> > q;

    int vis[N];

    void dij(int s, int t, double *d) {

        for(int i=1; i<=n; i++) d[i] = 1e15, vis[i] = 0;

        d[s] = 0; q.push(make_pair(0, s));

        while(!q.empty()) {

            int u = q.top().sec; q.pop();

            if(vis[u]) continue; vis[u] = 1;

            for(int i=h[u];i;i=e[i].ne) {

                int v = e[i].v;

                if(d[v] > d[u] + e[i].w)

                    d[v] = d[u] + e[i].w, q.push(make_pair(d[v], v));

            }

        }

    }

}

struct edge {int v, ne; double w;} e[M];

int cnt, h[N];

inline void ins(int u, int v, double w) {

    e[++cnt] = (edge){v, h[u], w}; h[u] = cnt;

}

double d_t[N]; int vis[N];

priority_queue<pdi, vector<pdi>, greater<pdi> > q;

void a_star(int s, int t) {

    I::dij(t, s, d_t);

    q.push(make_pair(d_t[s], s));

    while(!q.empty()) {

        int u = q.top().sec; double d = q.top().fir; q.pop();

        if(u == t) if((en -= d) < 0) return;

        vis[u]++;

        for(int i=h[u];i;i=e[i].ne) {

            int v = e[i].v;

            q.push(make_pair(d - d_t[u] + d_t[v] + e[i].w, v));

        }

    }

}

int main() {

    freopen("in", "r", stdin);

    n=read(); m=read(); scanf("%lf", &en); s=1; t=n;

    for(int i=1; i<=m; i++) u=read(), v=read(), scanf("%lf", &w), I::ins(v, u, w), ins(u, v, w);

    a_star(s, t);

    printf("%d\n", vis[t]);

}