暑期训练狂刷系列——Lightoj 1084 - Winter bfs

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 const int maxn = 100005;
 5 const int INF = 0x3f3f3f3f;
 6 int a[maxn], vis[maxn], n, k;
 7 struct node
 8 {
 9     int x, index;
10 };
11 
12 int solve ()
13 {
14     queue <node> Q;
15     node p, q;
16     
17     memset (vis, 0, sizeof(vis));
18     p.index = 0;
19     p.x = 0;
20     Q.push(p);
21     vis[0] = 1;
22     
23     while (!Q.empty())
24     {
25         p = Q.front();
26         Q.pop();
27         
28         if (p.index >= n)
29             return p.x;
30             
31         int temp = p.index;
32         while (temp<n && a[temp]-a[p.index]<=2*k)
33             temp ++;
34             
35         int num = temp - p.index;
36         if (num >= 3 && !vis[temp])
37         {
38             q.index = temp;
39             q.x = p.x + 1;
40             Q.push(q);
41             vis[temp] = 1;
42         }
43         if (num >= 4 && !vis[temp-1])
44         {
45             q.index = temp-1;
46             q.x = p.x + 1;
47             Q.push(q);
48             vis[temp-1] = 1;
49         }
50         if (num >= 5 && !vis[temp-2])
51         {
52             q.index = temp-2;
53             q.x = p.x + 1;
54             Q.push(q);
55             vis[temp-2] = 1;
56         }
57     }
58     return -1;
59 }
60 int main ()
61 {
62     int t, l = 0;
63     scanf ("%d", &t);
64     while (t --)
65     {
66         scanf ("%d %d", &n, &k);
67         for (int i=0; i<n; i++)
68             scanf ("%d", &a[i]);
69         sort (a, a+n);
70 
71         int res = solve();
72         printf ("Case %d: %d\n", ++l, res);
73     }
74 }