CodeForces 571B Minimization

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
LL a[300100],sum[300100];
LL dp[5050][5050];

int main()
{
    int n,k;
    while(~scanf("%d%d",&n,&k)){
        sum[0]=0;
        for(int i=1;i<=n;i++){
            scanf("%I64d",&a[i]);
            sum[i]=sum[i-1]+a[i];
        }
        sort(a+1,a+1+n);
        if(n<=k){
            printf("0\n");
            continue;
        }
        memset(dp,0,sizeof(dp));
        int l0=n/k;
        int l1=n/k+1;
        int len0=k-n%k,len1=n%k;
        a[0]=a[1];
        for(int i=0;i<=len0;i++){
            for(int j=0;j<=len1;j++){
                if(i==0&&j==0)continue;
                if(i){
                    k=(i-1)*l0+j*l1;
                    dp[i][j]=max(dp[i][j],dp[i-1][j]+a[k+1]-a[k]);
                }
                if(j){
                    k=i*l0+(j-1)*l1;
                    dp[i][j]=max(dp[i][j],dp[i][j-1]+a[k+1]-a[k]);
                }
            }
        }
        printf("%I64d\n",a[n]-a[1]-dp[len0][len1]);
    }
    return 0;
}