Codeforces Round #417 (Div. 2) C. Sagheer and Nubian Market(二分查找)

xiaoxiao2021-02-28  10

C. Sagheer and Nubian Market time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output

On his trip to Luxor and Aswan, Sagheer went to a Nubian market to buy some souvenirs for his friends and relatives. The market has some strange rules. It contains n different items numbered from 1 to n. The i-th item has base cost ai Egyptian pounds. If Sagheer buys kitems with indices x1, x2, ..., xk, then the cost of item xj is axj + xj·k for 1 ≤ j ≤ k. In other words, the cost of an item is equal to its base cost in addition to its index multiplied by the factor k.

Sagheer wants to buy as many souvenirs as possible without paying more than S Egyptian pounds. Note that he cannot buy a souvenir more than once. If there are many ways to maximize the number of souvenirs, he will choose the way that will minimize the total cost. Can you help him with this task?


The first line contains two integers n and S (1 ≤ n ≤ 105 and 1 ≤ S ≤ 109) — the number of souvenirs in the market and Sagheer's budget.

The second line contains n space-separated integers a1, a2, ..., an (1 ≤ ai ≤ 105) — the base costs of the souvenirs.


On a single line, print two integers kT — the maximum number of souvenirs Sagheer can buy and the minimum total cost to buy these ksouvenirs.

Examples input 3 11 2 3 5 output 2 11 input 4 100 1 2 5 6 output 4 54 input 1 7 7 output 0 0 Note

In the first example, he cannot take the three items because they will cost him [5, 9, 14] with total cost 28. If he decides to take only two items, then the costs will be [4, 7, 11]. So he can afford the first and second items.

In the second example, he can buy all items as they will cost him [5, 10, 17, 22].

In the third example, there is only one souvenir in the market which will cost him 8 pounds, so he cannot buy it.

题意:有一个奇怪的商店,出售东西的的价格按你买的个数会涨,每件物品的价格为 ai+k*mi。 ai为基础价格,k为你所要买的个数,mi为物品是第几个。



#include<stdio.h> #include<string.h> #include<algorithm> using namespace std; long long a[500000]={0}; long long cha[500000]={0}; int main() { int n; long long s; scanf("%d%lld",&n,&s); for(int i=1;i<=n;i++) { scanf("%lld",&a[i]); } long long l=1,r=n; long long summ=0; long long ans=0; while(l<=r) { long long mid=(l+r)>>1; for(int i=1;i<=n;i++) cha[i]=a[i]+i*mid; sort(cha+1,cha+1+n); summ=0; for(int i=1;i<=mid;i++) summ+=cha[i]; if(summ>s) r=mid-1; else l=mid+1; } for(int i=1;i<=n;i++) cha[i]=a[i]+i*r; sort(cha+1,cha+1+n); for(int i=1;i<=r;i++) ans+=cha[i]; printf("%lld %lld\n",r,ans); }