uva 1048 - Low Cost Air Travel（最短路）

题目链接：uva 1048 - Low Cost Air Travel

以两位状态为图上的一个节点，当前城市编号以及匹配上旅程上的p个城市。然后建图做dfs，并记录路径。

#include <cstdio>
#include <cstring>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

const int maxn = 50005;
const int maxm = 25;
const int inf = 0x3f3f3f3f;

struct Dijkstra {
struct Edge {
int u, v, w, rid;
Edge (int u = 0, int v = 0, int w = 0, int rid = 0): u(u), v(v), w(w), rid(rid) {}
};

struct State {
int u, d;
State(int u = 0, int d = 0): u(u), d(d) {}
bool operator < (const State& u) const { return d > u.d; }
};

int n, m, d[maxn], v[maxn], p[maxn], r[maxn];
vector<Edge> edges;
vector<int> G[maxn];

void init (int n) {
this->n = n;
edges.clear();
for (int i = 0; i < n; i++) G[i].clear();
}

void addEdge(int u, int v, int w, int rid) {
edges.push_back(Edge(u, v, w, rid));
m = edges.size();
G[u].push_back(m-1);
}

void putPath(int u) {
if (p[u] == -1) return;
u = p[u];
putPath(edges[u].u);
printf(" %d", edges[u].rid);
}

int dijkstra(int s, int e) {
memset(d, inf, sizeof(d));
memset(v, 0, sizeof(v));

p[s] = d[s] = 0;
p[s] = -1;
priority_queue<State> Q;
Q.push(State(s, d[s]));

while(!Q.empty()) {
int u = Q.top().u;
Q.pop();

if (v[u]) continue;
v[u] = 1;

for (int i = 0; i < G[u].size(); i++) {
Edge& e = edges[G[u][i]];
if (d[e.v] > d[u] + e.w) {
d[e.v] = d[u] + e.w;
p[e.v] = G[u][i];
Q.push(State(e.v, d[e.v]));
}
}
}
return d[e];
}
}solver;

int N, M, C, K, id[maxn][maxm], W[maxm];
vector<int> Ticket[maxm], Trip[maxm], Idx;

int find(int x) { return lower_bound(Idx.begin(), Idx.end(), x) - Idx.begin(); }
int ID(int s, int c) { int& x = id[s][c]; if (x == 0) x = ++K; return x; }

void init () {
Idx.clear();
K = 0;
memset(id, 0, sizeof(id));

int k, x;
for (int i = 1; i <= N; i++) {
Ticket[i].clear();
scanf("%d%d", &W[i], &k);
for (int j = 0; j < k; j++) {
scanf("%d", &x);
Ticket[i].push_back(x);
Idx.push_back(x);
}
}
scanf("%d", &M);
for (int i = 1; i <= M; i++) {
Trip[i].clear();
scanf("%d", &k);
for (int j = 0; j < k; j++) {
scanf("%d", &x);
Trip[i].push_back(x);
Idx.push_back(x);
}
}

sort(Idx.begin(), Idx.end());
C = unique(Idx.begin(), Idx.end()) - Idx.begin();
}

void solve (int x) {
solver.init(C * 11 + 1);
int sz = Trip[x].size();
for (int i = 1; i <= N; i++) {
int s = find(Ticket[i][0]);
for (int b = 0; b < sz; b++) {
int p = b;
for (int j = 1; j < Ticket[i].size(); j++) {
int e = find(Ticket[i][j]);
if (e == find(Trip[x][p])) p++;
solver.addEdge(ID(s, b), ID(e, p), W[i], i);
if (p >= sz) break;
}
}
//solver.addEdge(0, ID(s, s == find(Trip[x][0])), 0, 0);
//solver.addEdge(0, ID(s, 0), 0, 0);
}

int s = ID(find(Trip[x][0]), 1);

int e = ID(find(Trip[x][sz-1]), sz);
printf("Cost = %d\n", solver.dijkstra(s, e));
printf(" Tickets used:");
solver.putPath(e);
printf("\n");
}

int main () {
int cas = 1;
while (scanf("%d", &N) == 1 && N) {
init ();
for (int i = 1; i <= M; i++) {
printf("Case %d, Trip %d: ", cas, i);
solve(i);
}
cas++;
}
return 0;
}