HDU 6533 2019CCPC湖南全国邀请赛（广东省赛、江苏省赛）重现赛 B Build Tree（简单贪心模拟）

Problem Description

You need to construct a full n-ary tree(n叉树) with m layers.All the edges in this tree have a weight.But this weight cannot be chosen arbitrarily you can only choose from set S，the size of S is k，each element in the set can only be used once.Node 0 is the root of tree.

We use d(i) for the distance from root to node i.Our goal is to minimize the following expression:

min∑i=0Nd(i)

Please find the minimum value of this expression and output it.Because it may be a big number,you should output the answer modul p.

 

 

Input

The input file contains 2 lines.

The first line contains 4 integers,these respectively is k,m,n,p。(2 ≤ k ≤200000,2 ≤ p≤ 1015)

The second line contains k integers,represent the set S，the elements in the set guarantee less than or equal to 1015.

We guarantee that k is greater than or equal to the number of edges.

 

 

Output

The output file contains an integer.represent the answer.

 

 

Sample Input

5 2 3 10 1 2 3 4 5

 

 

Sample Output

6

 

 

Source

2019CCPC湖南全国邀请赛（广东省赛、江苏省赛）重现赛

 

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxx = 2e6+100;
long long p;
ll w[maxx];
ll a1[300];
ll a2[300];
int main(){
	ios::sync_with_stdio(0);
	ll n,k,m;
	while(cin>>k>>m>>n>>p){
		for(int i=1;i<=k;i++){
			cin>>w[i];
		}
		sort(w+1,w+1+k);
		if(m==1) cout<<0<<endl;
		else{
			ll kk=1;
			for(int i=1;i<m;i++){
				a1[i]=kk;
				a2[i]=a2[i-1]+a1[i];
				kk*=n;
			}	
			ll ans = 0;
			ll flag = a2[m-1]-1+kk;
			for(ll j=1;j<m;j++){
				for(ll i=1;i<=a1[m-j]*n;i++){
					ans = (ans%p+((w[flag--]%p)*(a2[j]%p)))%p;
				}
			}
			cout<<ans<<endl;
		}
	}	
	return 0;
}