This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "boxes.h"
#include <bits/stdc++.h>
using namespace std;
int getdist(int L, int l, int r) {
    //go from sections l to r, with L
    if (r<l) swap(l,r);
    return min(min(2*r,(L-l)*2),L);
}
long long delivery(int N, int K, int L, int p[]) {
    int k = K; int n = N;
    vector<int> vals(N);
    for (int i=0; i<N; i++) {
        vals[i] = p[i];
    }
    sort(vals.begin(), vals.end());
    int rem = N%K;
    long long co1 = 0;
    for (int i=0; i<=N-k; i+=k) {
        //i through i+k-1
        co1+=getdist(L,vals[i],vals[i+k-1]);
    }
    co1+=getdist(L,vals[N-rem-1],vals[N-1]);
    reverse(vals.begin(), vals.end());
    long long co2 = 0;
    for (int i=0; i<=N-k; i+=k) {
        //i through i+k-1
        co2+=getdist(L,vals[i],vals[i+k-1]);
    }
    co2+=getdist(L,vals[N-rem-1],vals[N-1]);
    long long co = min(co1,co2);
    return co;
}
Compilation message (stderr)
boxes.cpp: In function 'long long int delivery(int, int, int, int*)':
boxes.cpp:12:20: warning: unused variable 'n' [-Wunused-variable]
   12 |     int k = K; int n = N;
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