HDU 4179 Difficult Routes

链接

传送门

代码

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#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
using namespace std;
const double eps = 1e-8;
const int inf = 0x3f3f3f3f;
const int maxn = 10010;
const int maxm = 60010;
int x[maxn], y[maxn], z[maxn];
int u[maxm], v[maxm], dif[maxm];
double len[maxm >> 1];
struct Edge {
int from, to;
double dist;
Edge(int u, int v, double d): from(u), to(v), dist(d) {}
};
struct Dijkstra {
int n, m;
vector<Edge> edges;
vector<int> G[maxn];
bool done[maxn];
double d[maxn];
int p[maxn];
void init(int n) {
this->n = n;
for (int i = 0; i <= n; ++i) {
G[i].clear();
}
edges.clear();
}
void AddEdge(int from, int to, double dist) {
edges.push_back(Edge(from, to, dist));
m = int(edges.size());
G[from].push_back(m - 1);
}
struct HeapNode {
double d;
int u;
HeapNode(double d, int u): d(d), u(u) {}
bool operator < (const HeapNode& rhs) const {
return d > rhs.d;
}
};
void dijkstra(int s) {
priority_queue<HeapNode> Q;
for (int i = 0; i < n; ++i) {
d[i] = inf;
}
d[s] = 0;
memset(done, 0, sizeof done);
Q.push(HeapNode(0, s));
while (!Q.empty()) {
HeapNode x = Q.top();
Q.pop();
int u = x.u;
if (done[u]) {
continue;
}
done[u] = true;
for (int i = 0; i < G[u].size(); ++i) {
Edge& e = edges[G[u][i]];
if (d[e.to] > d[u] + e.dist) {
d[e.to] = d[u] + e.dist;
p[e.to] = G[u][i];
Q.push(HeapNode(d[e.to], e.to));
}
}
}
}
} a, b;
int Dif(int i, int j) {
if (z[j] <= z[i]) {
return 0;
}
return floor(100.0 * (z[j] - z[i]) / sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])));
}
double Dis(int i, int j) {
return sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]) + (z[i] - z[j]) * (z[i] - z[j]));
}
int main() {
int n, m;
while (~scanf("%d%d", &n, &m) && (n || m)) {
a.init(n + 1), b.init(n + 1);
for (int i = 0; i < n; ++i) {
scanf("%d%d%d", &x[i], &y[i], &z[i]);
}
m <<= 1;
for (int i = 0; i < m; i += 2) {
scanf("%d%d", &u[i], &v[i]);
v[i + 1] = --u[i], u[i + 1] = --v[i];
len[i >> 1] = Dis(u[i], v[i]);
}
int s, t, d;
scanf("%d%d%d", &s, &t, &d);
--s, --t;
for (int i = 0; i < m; ++i) {
dif[i] = Dif(u[i], v[i]);
double l = len[i >> 1];
if (dif[i] <= d) {
a.AddEdge(u[i], v[i], l);
b.AddEdge(v[i], u[i], l);
}
}
a.dijkstra(s), b.dijkstra(t);
double ans = inf;
for (int i = 0; i < m; ++i) {
if (dif[i] == d) {
double l = a.d[u[i]] + b.d[v[i]] + len[i >> 1];
if (l < ans) {
ans = l;
}
}
}
if (fabs(ans - inf) < eps) {
puts("None");
} else {
printf("%.1f\n", ans);
}
}
return 0;
}

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