Codeforces Round #417 (Div. 2) C. Sagheer and Nubian Market ---- 贪心+二分★

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题目传送门

做法：二分k值，处理式子存到数组，排序后，优先拿取前面k个最小的即可。

AC代码：

#include<bits/stdc++.h>
#define IO          ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define pb(x)       push_back(x)
#define sz(x)       (int)(x).size()
#define sc(x)       scanf("%d",&x)
#define pr(x)       printf("%d\n",x)
#define abs(x)      ((x)<0 ? -(x) : x)
#define all(x)      x.begin(),x.end()
#define mk(x,y)     make_pair(x,y)
#define debug       printf("!!!!!!\n")
#define fin         freopen("in.txt","r",stdin)
#define fout        freopen("out.txt","w",stdout)
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
const double PI = 4*atan(1.0);
const int maxm = 1e8+5;
const int maxn = 1e5+5;
const int INF = 0x3f3f3f3f;
const ll LINF = 1ll<<62;
ll a[maxn];
ll sum[maxn];
int n;
ll s,res;
bool check(int mid)
{
    for(int i=1;i<=n;i++) sum[i] = a[i]+1ll*(i)*mid;
    sort(sum+1,sum+n+1);
    for(int i=1;i<=mid;i++) sum[i] = sum[i]+sum[i-1];
    res = sum[mid];
    return sum[mid]<=s;
}
int main()
{
    #ifdef LOCAL_FILE
    fin;
    #endif // LOCAL_FILE
    IO;
    cin>>n>>s;
    for(int i=1;i<=n;i++) cin>>a[i];
    int l = 1,r = n;
    ll ans = LINF;
    int cnt = -1;
    while(l<=r)
    {
        int mid = (r-l)/2+l;
        if(check(mid)){
            cnt = mid;
            ans = res;
            l = mid+1;
            //cout<<l<<" "<<r<<endl;
        }
        else r = mid-1;
    }
    if(ans!=LINF) cout<<cnt<<" "<<ans<<endl;
    else cout<<0<<" "<<0<<endl;
    return 0;
}