HDU 6005 Pandaland——dijkstra + 剪枝

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#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;}
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