BZOJ3931【最大流】【SPFA】

/* I will wait for you */    
    
#include <cstdio>    
#include <cstdlib>    
#include <cstring>    
#include <cmath>    
#include <ctime>    
#include <algorithm>    
#include <iostream>    
#include <fstream>    
#include <vector>    
#include <queue>    
#include <deque>    
#include <set>    
#include <map>    
#include <string>    
#define make make_pair    
#define fi first    
#define se second    
    
using namespace std;    
    
typedef long long ll;    
typedef unsigned long long ull;    
typedef pair<int, int> pii;    
    
const int maxn = 500010;    
const int maxm = 1010;    
const int maxs = 26;    
const int inf = 0x3f3f3f3f;    
const int P = 1000000007;    
const double error = 1e-9;    
    
inline ll read()    
{    
    ll x = 0, f = 1;    
    char ch = getchar();    
    while (ch < '0' || ch > '9')    
          f = (ch == '-' ? -1 : 1), ch = getchar();    
    while (ch >= '0' && ch <= '9')    
          x = x * 10 + ch - '0', ch = getchar();    
    return x * f;    
}    

struct edgc
{
	int u, v;
	ll w;
	int next;
} c[maxn];

struct edge
{
	int v;
	ll a;
	int next;
} e[maxn];

int n, m, s, t, cntc, cnte, head[maxn],
    hcad[maxn], vis[maxn], cur[maxn];
ll dis[maxn];

void inscrt(int u, int v, ll w)
{
	c[cntc] = (edgc) {u, v, w, hcad[u]};
	hcad[u] = cntc++;
	c[cntc] = (edgc) {v, u, w, hcad[v]};
	hcad[v] = cntc++;
}	

void insert(int u, int v, ll a)
{
	e[cnte] = (edge) {v, a, head[u]};
	head[u] = cnte++;
	e[cnte] = (edge) {u, 0, head[v]};
	head[v] = cnte++;
}

int q[maxn];

void spfa()
{
	for (int i = 1; i <= n; i++)
		dis[i] = (ll) inf * inf, vis[i] = 0;
	
	int he = 0, ta = 1; q[0] = 1, dis[1] = 0;

	while (he != ta) {
		int u = q[he++]; vis[u] = 0, he %= maxn;

		for (int i = hcad[u]; i != -1; i = c[i].next) {
			int v = c[i].v;
			if(dis[v] > dis[u] + c[i].w) {
				dis[v] = dis[u] + c[i].w;
				if (!vis[v]) {
					vis[v] = 1;
					q[ta++] = v, ta %= maxn;
				}
			}
		}
	}

	for (int i = 0; i < cntc; i++) {
		int u = c[i].u, v = c[i].v;
		if (dis[u] + c[i].w == dis[v])
			insert(n + u, v, (ll) inf * inf);
	}
}

bool bfs()
{
	for (int i = 1; i <= t; i++)
		dis[i] = -1;
	
	int he = 0, ta = 1; q[0] = s, dis[s] = 0;

	while (he != ta) {
		int u = q[he++];

		for (int i = head[u]; i != -1; i = e[i].next) {
			int v = e[i].v;
			if (e[i].a && dis[v] == -1)
				dis[v] = dis[u] + 1, q[ta++] = v;
		}
	}

	return dis[t] != -1;
}

ll dfs(int u, ll a)
{
	if (u == t)
		return a;

	ll f, flow = 0;
	for (int i = cur[u]; a && i != -1; i = e[i].next) {
		int v = e[i].v;
		if(e[i].a && dis[v] == dis[u] + 1) {
			f = dfs(v, min(a, e[i].a));
			e[i].a -= f, e[i ^ 1].a += f;
			a -= f, flow += f;
			if (e[i].a) cur[u] = i;
		}
	}

	if (!flow) dis[u] = -1;
	return flow;
}

ll dinic()
{
	ll flow = 0;

	while(bfs()) {
		for (int i = 1; i <= t; i++)
			cur[i] = head[i];
		flow += dfs(s, (ll) inf * inf);
	}

	return flow;
}


int main()
{
	n = read(), m = read();

	memset(head, -1 ,sizeof head);
	memset(hcad, -1 ,sizeof hcad);

	for (int i = 0; i < m; i++) {
		int u = read(), v = read();
		ll w = read();
		inscrt(u, v, (ll) w);
	}

	spfa();

	s = 1, t = 2 * n;

	for (int i = 1; i <= n; i++) {
		ll c = read();
		if (i != 1 && i != n)
			insert(i, n + i, (ll) c);
		else 
			insert(i, n + i, (ll) inf * inf);
	}

	ll ans = dinic();

	printf("%lld\n", ans);

	return 0;
}