HDU 6005 Pandaland——dijkstra + 剪枝

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <functional>
using namespace std;
typedef pair<int, int> P;
const int INF = 0x3f3f3f3f;
const int maxn = 1e4 + 10;
int T, n, cnt, ans, d[maxn], vis[maxn];
struct Edge {
    int u, v, cost;
}edge[maxn];
vector<P> G[maxn];
map<P, int> m;
void init() {
    cnt = 0; ans = INF;
    for (int i = 0; i < maxn; i++) {
        G[i].clear();
    }
    m.clear();
}
void dijkstra(int s, int e, int x) {
    for (int i = 0; i < maxn; i++) {
        d[i] = INF;
        vis[i] = 0;
    }
    d[s] = 0;
    priority_queue<P, vector<P>, greater<P> > q;
    q.push(make_pair(0, s));
    while (!q.empty()) {
        P p = q.top(); q.pop();
        int u = p.second, dis = p.first;
        if (dis + x >= ans) break;
        if (vis[u]) continue;
        vis[u] = 1;
        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i].first, id = G[u][i].second;
            int cost = edge[id].cost;
            if (d[v] > d[u] + cost) {
                d[v] = d[u] + cost;
                q.push(make_pair(d[v], v));
            }
        }
    }
    ans = min(ans, d[e] + x);
}
int main() {
    scanf("%d", &T);
    for (int kase = 1; kase <= T; kase++) {
        scanf("%d", &n);
        init();
        for (int i = 1; i <= n; i++) {
            int x1, y1, x2, y2, w;
            scanf("%d %d %d %d %d", &x1, &y1, &x2, &y2, &w);
            P p1 = make_pair(x1, y1), p2 = make_pair(x2, y2);
            if (!m[p1]) m[p1] = ++cnt;
            if (!m[p2]) m[p2] = ++cnt;
            int u = m[p1], v = m[p2];
            G[u].push_back(make_pair(v, i)); G[v].push_back(make_pair(u, i));
            edge[i].u = u, edge[i].v = v, edge[i].cost = w;
        }
        for (int i = 1; i <= n; i++) {
            int u = edge[i].u, v = edge[i].v, cost = edge[i].cost;
            edge[i].cost = INF;
            dijkstra(u, v, cost);
            edge[i].cost = cost;
        }
        if (ans == INF) ans = 0;
        printf("Case #%d: %d\n", kase, ans);
    }
    return 0;
}