hdu5884 Sort（二分+k叉哈夫曼树）

 1 #include<cstdio>
 2 #include<queue>
 3 #include<algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 const int N = 100001;
 7 int n, m;
 8 int a[N];
 9 int jud(int k){
10     int i;
11     int tt = (n-1)%(k-1);
12     ll t, s = 0;
13     queue<ll>q1, q2;
14     if(tt){
15         for(i = 1; i <= k-1 - tt; ++i)
16             q1.push(0);//虚拟点
17     }
18     for(i = 1; i <= n; ++i)
19         q1.push(a[i]);
20     while(1){
21         t = 0;
22         int x1, x2;
23         for(i = 1; i <= k; ++i){
24             if(q1.empty() && q2.empty())
25                 break;
26             if(q1.empty()){
27                 t += q2.front(); q2.pop();
28                 continue;
29             }
30             if(q2.empty()){
31                 t += q1.front(); q1.pop();
32                 continue;
33             }
34             x1 = q1.front();
35             x2 = q2.front();
36             if(x1 < x2){
37                 t += x1; q1.pop();
38             }else{
39                 t += x2; q2.pop();
40             }
41         }
42         s += t;
43         if(q1.empty() && q2.empty())
44             break;
45         q2.push(t);//维护合并后的值
46     }
47     if(s <= m) return 1;
48     return 0;
49 }
50 void bi_search(){
51     int l = 2,r = n;
52     while(l < r){
53         int mid = l + (r - l)/2;
54         if(jud(mid))
55             r = mid;
56         else
57             l = mid + 1;
58     }
59     printf("%d\n", r);
60 }
61 int main(){
62     int t, i;
63     scanf("%d", &t);
64     while(t--){
65         scanf("%d%d", &n, &m);
66         for(i = 1; i <= n; ++i)
67             scanf("%d", &a[i]);
68         sort(a+1, a+1+n);
69         bi_search();
70     }
71     return 0;
72 }