poj 1511 Invitation Cards 最短路

       这题看了很久才看明白题意，就是求最短路，正向图，反向图求最短路，然后求和

       这题数据规模很大，分别用了spfa和Dijkstra+heap实现，发现这两个算法差别不大，都在2s左右，Dij+heap貌似快spfa一些

 

#include <iostream>

#include <queue>

#include <cstring>

#include <cstdio>

using namespace std;



const int MAX = 2000010;

const int N =  1000005;

const long long INF = 10000000000;



struct Node

{

	int v;

	int cost;

	int next;

};



Node node[MAX];

int d[N], d2[N];

bool in_q[N];

int cnt[N];

int adj[N];

int adj2[N];

int n, m;

int size;



void add_edge(int u, int v, int cost, int* adj)

{

	node[size].v = v;

	node[size].cost = cost;

	node[size].next = adj[u];

	adj[u] = size++;

}



bool spfa(int* adj, int *d)

{

	memset(cnt, 0, sizeof(cnt));

	memset(in_q, 0, sizeof(in_q));

	for (int i = 0; i <= n; i++)

		d[i] = INF;



	d[1] = 0;

	queue<int> Q;

	in_q[1] = true;

	Q.push(1);

	int u, v, w;



	while (!Q.empty())

	{

		u = Q.front();

		Q.pop();

		in_q[u] = false;



		for (int i = adj[u]; i != -1; i = node[i].next)

		{

			v = node[i].v;

			w = node[i].cost;



			if (d[v] > d[u] + w)

			{

				d[v] = d[u] + w;



				if (!in_q[v])

				{

					in_q[v] = true;

					Q.push(v);



					if (++cnt[v] > n) return false;

				}

			}

		}

	}



	return true;

}



struct cmp

{

	bool operator() (const int& a, const int &b)

	{

		return d[a] > d[b];

	}

};



void Dijkstra(int *adj, int *d)

{

	for (int i = 0; i <= n; i++)

		d[i] = INF;

	d[1] = 0;

	priority_queue<int, vector<int>, cmp> Q;



	Q.push(1);

	int u, v, w;

	while (!Q.empty())

	{

		u = Q.top();

		Q.pop();



		for (int i = adj[u]; i != -1; i = node[i].next)

		{

			v = node[i].v;

			w = node[i].cost;



			if (d[v] > d[u] + w)

			{

				d[v] = d[u] + w;

				Q.push(v);

			}

		}

	}

}





int main()

{

	int cases;

	int a, b, c;



	scanf("%d", &cases);



	while (cases--)

	{

		scanf("%d%d", &n, &m);



		for (int i = 0; i <= n; i++)

		{

			adj[i] = -1;

			adj2[i] = -1;

		}



		size = 0;

		for (int i = 0; i < m; i++)

		{

			scanf("%d%d%d", &a, &b, &c);

			add_edge(a, b, c, adj);

			add_edge(b, a, c, adj2);

		}



		spfa(adj, d);

		spfa(adj2, d2);

		long long ans = 0;



		for (int i = 2; i <= n; i++)

			ans = ans + d[i] + d2[i];



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

	}

	return 0;

}