luoguP1951 收费站_NOI导刊2009提高（2） 

 1 #include <bits/stdc++.h>
 2 #define inf 2147483647
 3 using namespace std;
 4 int n, m, u, v, s, f[10005], e[10005], head[1000500], d[10005], ans, tot, l, r;
 5 void input() {
 6     freopen("input.txt", "r", stdin);
 7     // freopen("output.txt","w",stdout);
 8 }
 9 struct A {
10     int v, w, next;
11 } lu[1000500];
12 void add(int x, int y, int z) {
13     lu[++tot].v = y;
14     lu[tot].w = z;
15     lu[tot].next = head[x];
16     head[x] = tot;
17 }
18 void read() {
19     int a, b, c;
20     scanf("%d%d%d%d%d", &n, &m, &u, &v, &s);
21     for (int i = 1; i <= n; i++) {
22         scanf("%d", &f[i]);
23         e[i] = f[i];
24     }
25     sort(e + 1, e + n + 1);
26     for (int i = 1; i <= m; i++) {
27         scanf("%d%d%d", &a, &b, &c);
28         add(a, b, c);
29         add(b, a, c);
30     }
31 }
32 deque<int> q;
33 bool spfa(long long minn) {
34     for (int i = 0; i <= n; i++) d[i] = inf;
35     q.push_back(u);
36     d[u] = 0;
37     while (q.size()) {
38         int now = q.front();
39         q.pop_front();
40         if (f[now] > minn)
41             continue;
42         for (int i = head[now]; i; i = lu[i].next) {
43             if (f[lu[i].v] > minn)
44                 continue;
45             if (d[lu[i].v] > d[now] + lu[i].w) {
46                 d[lu[i].v] = d[now] + lu[i].w;
47                 if (q.size() && d[lu[i].v] < d[q.front()])
48                     q.push_front(lu[i].v);
49                 else
50                     q.push_back(lu[i].v);
51             }
52         }
53     }
54     return d[v] <= s;
55 }
56 void work() {
57     int l = 1, r = n;
58     while (l <= r) {
59         int j = (l + r) >> 1;
60         if (spfa(e[j])) {
61             ans = e[j];
62             r = j - 1;
63         } else
64             l = j + 1;
65     }
66     if (ans == 0)
67         printf("-1\n");
68     else
69         printf("%d\n", ans);
70 }
71 int main() { 
72  // input();
73     read();
74     work();
75     return 0;
76 }
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posted @ 2019-06-12 12:01  Achen_sy  阅读(161)  评论(0)    收藏  举报