[BZOJ 1975][Sdoi2010]魔法猪学院

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define maxn 5010
#define M 200010
using namespace std;

int n, m, ans;
double tot, dis[maxn];
const double inf = 1e12;
bool vis[maxn];

struct Node{
double st, ed;
int l, r, am, dis;
bool operator<(const Node& k)const{
return st > k.st;
}
Node(double _ = 0, double __ = 0, int val = 0, int l = 0, int r = 0, int dis = 0):
st(_), ed(__), am(val), l(l), r(r), dis(dis){}
};
Node T[1850010];
int root, size;

int merge(int a, int b){
if(!a || !b)return a + b;
if(T[a] < T[b])swap(a, b);
T[a].r = merge(T[a].r, b);
if(T[T[a].l].dis < T[T[a].r].dis)
swap(T[a].l, T[a].r);
T[a].dis = T[a].r ? T[T[a].r].dis + 1 : 0;
return a;
}
Node TMP;
void Get_pop(){
TMP = T[root];
root = merge(T[root].l, T[root].r);
}

queue<int>Q;

struct solver{
int h[maxn], cnt;
int nxt[M], to[M];
double w[M];
void add(int u, int v, double d){
cnt ++;
to[cnt] = v;
w[cnt] = d;
nxt[cnt] = h[u];
h[u] = cnt;
}

void Spfa(){
for(int i = 1; i <= n; i ++)dis[i] = inf;
Q.push(n);dis
= 0;
while(!Q.empty()){
int u = Q.front();Q.pop();
for(int i = h[u]; i; i = nxt[i]){
int v = to[i];
if(dis[v] > dis[u] + w[i]){
dis[v] = dis[u] + w[i];
if(!vis[v]){
vis[v] = true;
Q.push(v);
}
}
}vis[u] = false;
}
}

void Astar(){
T[++ size] = Node(dis[1], 0, 1);root = size;
while(true){
Get_pop();int u = TMP.am;
for(int i = h[u]; i; i = nxt[i]){
int v = to[i];
T[++ size] = Node(TMP.ed + w[i] + dis[v], TMP.ed + w[i], v);
root = merge(root, size);
}

if(u == n){
tot -= TMP.ed;
if(tot < 0)return;
ans ++;
}
}
}
}G0, G1;

int main(){
#ifndef ONLINE_JUDGE
freopen("magic.in", "r", stdin);
freopen("magic.out", "w", stdout);
#endif
scanf("%d%d%lf", &n, &m, &tot);
int u, v; double w;
for(int i = 1; i <= m; i ++){
scanf("%d%d%lf", &u, &v, &w);
G0.add(u, v, w), G1.add(v, u, w);
}
G1.Spfa();
G0.Astar();
printf("%d\n", ans);
return 0;
}