cf812c
Thinking
贪心 + 二分
Answer
#include <iostream>
#include <algorithm>
using namespace std;
int k; // the amount of items
struct item{
long long price;
long long pos;
};
bool compare(item a, item b){
return a.price + a.pos * k < b.price + b.pos * k;
}
int main(){
// input
int n, S;
cin >> n >> S;
item items[n];
for (int i = 0; i < n; ++i) {
cin >> items[i].price;
items[i].pos = i + 1;
}
// work
int kok = 0; long long tot = S;
int low = 1, high = n;
while (low <= high){
k = low + high >> 1;
stable_sort(items, items+n, compare);
// total prices
long long t = 0;
for (int i = 0; i < k; ++i) {
t += items[i].price + items[i].pos * k;
}
if (t < S && t > 0){
if ((t < tot && k == kok) || k > kok){
tot = t;
kok = k;
}
low = k+1;
}
else if (t == S){
tot = t;
kok = k;
break;
}
else{
high = k-1;
}
}
if (kok == 0) tot = 0;
cout << kok << " " << tot << endl;
}