#include <bits/stdc++.h>
using namespace std;
const int N = 1e7 + 7;
const long long inf = 1e18 + 7;
vector<long long> v1, v2, v3, v4;
void output(vector<long long> v){
for(long long &x: v){
cout << x << " ";
}
cout << endl;
}
long long delivery(int n, int k, int l, int *positions){
sort(positions, positions + n);
int idx = 0;
for(; idx < n && positions[idx] <= l / 2; idx++){
v1.push_back(positions[idx]);
}
for(; idx < n; idx++){
v2.push_back(l - positions[idx]);
}
if(!v2.empty()){
reverse(v2.begin(), v2.end());
}
for(int i = 0 ; i < (int)v1.size(); i++){
if(i >= k){
pr1.push_back(pr1[i - k] + v1[i] * 2ll);
}
else{
pr1.push_back(v1[i] * 2ll);
}
}
for(int i = 0 ; i < (int)v2.size(); i++){
if(i >= k){
pr2.push_back(pr2[i - k] + v2[i] * 2ll);
}
else{
pr2.push_back(v2[i] * 2ll);
}
}
long long ans = 0, sum1 = 0, sum2 = 0;
for(int i = -1; true;){
if(i + k >= (int)v1.size()){
for(++i; i < (int)v1.size(); ++i){
v3.push_back(v1[i]);
}
break;
}
i += k;
sum1 += (long long)v1[i] * 2ll;
}
for(int i = -1; true;){
if(i + k >= (int)v2.size()){
for(++i; i < (int)v2.size(); ++i){
v4.push_back(v2[i]);
}
break;
}
i += k;
sum2 += (long long)v2[i] * 2ll;
}
ans = sum1 + sum2;
if(v3.empty() || v4.empty()){
if(!v3.empty()){
ans += v3.back() * 2ll;
}
if(!v4.empty()){
ans += v4.back() * 2ll;
}
return ans;
}
if((int)v3.size() + (int)v4.size() <= k){
ans += min((long long)l, v3.back() * 2ll + v4.back() * 2ll);
return ans;
}
ans = pr1.back() + pr2.back();
return ans;
}
/*int positions[N], n, k, l;
int main(){
cin >> n >> k >> l;
for(int i = 0; i < n; i++){
cin >> positions[i];
}
cout << delivery(n, k, l, positions) << "\n";
return 0;
}*/
/*
3 2 8
1 2 5
*/
Compilation message
boxes.cpp: In function 'long long int delivery(int, int, int, int*)':
boxes.cpp:34:4: error: 'pr1' was not declared in this scope
pr1.push_back(pr1[i - k] + v1[i] * 2ll);
^~~
boxes.cpp:37:4: error: 'pr1' was not declared in this scope
pr1.push_back(v1[i] * 2ll);
^~~
boxes.cpp:43:4: error: 'pr2' was not declared in this scope
pr2.push_back(pr2[i - k] + v2[i] * 2ll);
^~~
boxes.cpp:46:4: error: 'pr2' was not declared in this scope
pr2.push_back(v2[i] * 2ll);
^~~
boxes.cpp:93:8: error: 'pr1' was not declared in this scope
ans = pr1.back() + pr2.back();
^~~
boxes.cpp:93:21: error: 'pr2' was not declared in this scope
ans = pr1.back() + pr2.back();
^~~