Problem Description
Given the sequence A with n integers t1,t2,⋯,tn. Given the integral coefficients a and b. The fact that select two elements ti and tj of A and i≠j to maximize the value of at2i+btj, becomes the largest point.
Input
An positive integer T, indicating there are T test cases.
For each test case, the first line contains three integers corresponding to n (2≤n≤5×106), a (0≤|a|≤106) and b (0≤|b|≤106). The second line contains n integers t1,t2,⋯,tn where 0≤|ti|≤106 for 1≤i≤n.
The sum of n for all cases would not be larger than 5×106.
Output
The output contains exactly T lines.
For each test case, you should output the maximum value of at2i+btj.
Sample Input
2
3 2 1
1 2 3
5 -1 0
-3 -3 0 3 3
Sample Output
Case #1: 20
Case #2: 0
Source
2015 ACM/ICPC Asia Regional Shenyang Online
Recommend
wange2014
#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<bits/stdc++.h>
#define ll long long
using namespace std;
struct nana
{
long long m,n;
}A[500010],B[500010];
int cmp(nana a,nana b)
{
return a.m<b.m;
}
int main()
{
int T;
ll flag=0;
scanf("%d",&T);
while(T--)
{
ll n,a,b,t;
scanf("%lld%lld%lld",&n,&a,&b);
for(ll i=0;i<n;i++)
{
scanf("%lld",&t);
A[i].m=a*t*t;
A[i].n=i;
B[i].m=b*t;
B[i].n=i;
}
sort(A,A+n,cmp);
sort(B,B+n,cmp);
printf("Case #%lld: %lld\n",++flag,(A[n-1].n==B[n-1].n)?(max(A[n-1].m+B[n-2].m,A[n-2].m+B[n-1].m)):(A[n-1].m+B[n-1].m));
}
return 0;
}