HDU 5461:Largest Point
Largest Point
Time Limit: 1500/1000 MS (Java/Others) Memory Limit: 65535/32768 K (Java/Others)Total Submission(s): 1102 Accepted Submission(s): 429
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 ton (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 ofn for
all cases would not be larger than 5×106 .
For each test case, the first line contains three integers corresponding to
The sum of
Output
The output contains exactly T lines.
For each test case, you should output the maximum value ofat2i+btj .
For each test case, you should output the maximum value of
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
题意给了a b的两个值,然后给了一大堆t的值,问在这些t的值里面求最大的
分情况讨论,对于a大于零小于零,b大于零小于零。然后记录最大值 次大值 最小值 次小值 还有一个绝对值最小值,这五个值就够用了。
代码:
#include <iostream> #include <algorithm> #include <cmath> #include <vector> #include <string> #include <cstring> #pragma warning(disable:4996) using namespace std; long long test, n, a, b; long long i, j; long long abs_min, max1, max2, min1, min2; int main() { long long temp; cin >> test; for (i = 1; i <= test; i++) { abs_min = 1000005; max1 = -1000005; max2 = -1000005; min1 = 1000005; min2 = 1000005; cin >> n >> a >> b; for (j = 1; j <= n; j++) { scanf("%lld",&temp); if (abs(temp) < abs_min) { abs_min = abs(temp); } if (temp > max1) { max2 = max1; max1 = temp; } else if (temp > max2) { max2 = temp; } if (temp < min1) { min2 = min1; min1 = temp; } else if (temp < min2) { min2 = temp; } } long long res; if (a >= 0 && b>=0) { res = a*max1* max1 + b*max2; res = max(res, a*min1 * min1 + b*max1); } else if (a >= 0 && b <= 0) { res = a*max1 * max1 + b*min1; res = max(res, a*min1 * min1 + b*min2); } else if (a <= 0 && b <= 0) { if (min1 == abs_min) { res = a*abs_min*abs_min + b*min2; } else { res = a*abs_min*abs_min + b*min1; } } else { if (max1 == abs_min) { res = a*abs_min*abs_min + b*max2; } else { res = a*abs_min*abs_min + b*max1; } } cout << "Case #"<<i<<": "<<res<< endl; } return 0; }
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