UVa 10986 Sending email 优先队列优化的dijkstra 和 朴素dijkstra 效率对比

/***   原来是想把这题用来dijkstra练手的，突然到不如来测测dijkstra用优先队列优化之后效率的变化情况*   本想如果优化效果不是很明显的话，就无所谓用哪个了。。结果。。。这题居然。。。不优化就T ！！*   直接上代码了。。dijkstra()是朴素的  dijkstra_q() 是优先队列优化后的。*/#include <cstdio>#include <iostream>#include <cstring>#include <cmath>#include <string>#include <queue>#include <map>#include <vector>#include <algorithm>#define DEBUG 0#define INF 0x1fffffff#define MAXS 20005typedef long long LL;using namespace std;int dis[MAXS], vis[MAXS];int n, m, s, e;struct Edge {    int v, w;    Edge() {}    Edge(int vv, int ww) {v = vv; w = ww;}};struct Node {    int v, d;    Node() {}    Node(int vv, int dd) {v = vv; d = dd;}    bool operator < (const Node &a) const {        return d > a.d;    }};vector<Edge> ver[MAXS];void init(){    for(int i = 0; i <= n; i ++)    {        dis[i] = INF;        vis[i] = 0;        ver[i].clear();    }}void dijkstra(){    dis[s] = 0;    int curMin = 0;    while(curMin != INF)    {        int pos;        curMin = INF;        for(int i = 0; i < n; i ++) {            if(!vis[i] && dis[i] < curMin)            {                curMin = dis[i];                pos = i;            }        }        if(curMin == INF) break;        vis[pos] = 1;        for(int i = 0; i != ver[pos].size(); i ++)        {            int v = ver[pos][i].v, w = ver[pos][i].w;            if(!vis[v] && dis[v] > dis[pos] + w) {                dis[v] = dis[pos] + w;            }        }    }}void dijkstra_q(){    priority_queue<Node> pq;    dis[s] = 0;    pq.push(Node(s, 0));    while(!pq.empty())    {        Node cur = pq.top(); pq.pop();        if(vis[cur.v]) continue;        vis[cur.v] = 1;        if(cur.v == e) break;        for(int i = 0; i != ver[cur.v].size(); i ++)        {            int v = ver[cur.v][i].v, w = ver[cur.v][i].w;            if(!vis[v] && dis[v] > dis[cur.v] + w)            {                dis[v] = dis[cur.v] + w;                pq.push(Node(v, dis[v]));            }        }    }}int main(){    int cases; cin >> cases;    for(int curCase = 1; curCase <= cases; curCase ++)    {        cin >> n >> m >> s >> e;        init();        for(int i = 1; i <= m; i ++)        {            int u, v, w;            cin >> u >> v >> w;            ver[u].push_back(Edge(v, w));            ver[v].push_back(Edge(u, w));        }        dijkstra_q();        if(dis[e] == INF) cout << "Case #" << curCase << ": unreachable" << endl;        else    cout << "Case #" << curCase << ": " << dis[e] << endl;    }    return 0;}