fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int fun(vector<int> &A, int B) {
  5.     int n = A.size();
  6.     int suff[n + 1];  // Suffix sum array
  7.     suff[n] = 0;  // Extra element for ease
  8.     suff[n - 1] = A[n - 1];
  9.  
  10.     // Compute suffix sum from right to left
  11.     for (int i = n - 2; i >= 0; i--)
  12.         suff[i] = A[i] + suff[i + 1];
  13.  
  14.     int prefSum = 0;  // Sum from left
  15.     int ans = suff[n - B];  // Taking all B elements from right
  16.  
  17.     // Try taking 'i' elements from left and remaining from right
  18.     for (int i = 0; i < B; i++) {
  19.         prefSum += A[i];  // Add current left element
  20.         int suffSum = suff[n - B + (i + 1)];  // Remaining elements from right
  21.         ans = max(ans, prefSum + suffSum);
  22.     }
  23.     return ans;
  24. }
  25.  
  26. int solve(vector<int> &A, int B) {
  27.     return fun(A, B);
  28. }
  29.  
  30. int main() {
  31.     vector<int> A = {5, -2, 3, 1, 2};
  32.     int B = 3;
  33.     cout << solve(A, B);
  34.     return 0;
  35. }
  36.  
Success #stdin #stdout 0.01s 5288KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
8
https://ideone.com/PZwh77
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!