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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. typedef long long ll;
  5.  
  6. long getMinimumCost(vector<int> cost, int minWeight) {
  7.     int n = cost.size();
  8.  
  9.     // (cost per weight, weight, cost)
  10.     vector<tuple<double, int, int>> items;
  11.  
  12.     long long temp = 1ll;
  13.  
  14.     for (int i = 0; i < n; i++) {
  15.         double efficiency = (double)cost[i] / temp; // i+1 is the weight
  16.         items.push_back({efficiency, temp, cost[i]});
  17.         temp *= 2ll;
  18.     }
  19.  
  20.     // Sort by efficiency (smallest first)
  21.     sort(items.begin(), items.end());
  22.  
  23.     ll totalCost = 0;
  24.     int weightAchieved = 0;
  25.  
  26.     ll ans = LLONG_MAX;
  27.  
  28.  
  29.     for (auto [eff, weight, cst] : items) {
  30.         if (weightAchieved >= minWeight) break;
  31.  
  32.         // How many units needed?
  33.         int needed = (minWeight - weightAchieved + weight - 1) / weight; // ceil
  34.  
  35.         totalCost += (ll)needed * cst;
  36.         weightAchieved += (ll)needed * weight;
  37.  
  38.         ans = min(ans, totalCost);
  39.  
  40.         if (weightAchieved == minWeight) break;
  41.  
  42.         totalCost -= cst;
  43.         weightAchieved -= weight;
  44.     }
  45.  
  46.     return ans;
  47. }
  48.  
  49. int main() {
  50.     int n = 5;
  51.     vector<int> cost = {2, 5, 7, 11, 25};
  52.     int minWeight = 26;
  53.  
  54.     cout << getMinimumCost(cost, minWeight) << endl;
  55.  
  56.     return 0;
  57. }
  58.  
Success #stdin #stdout 0.01s 5300KB
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https://ideone.com/Wtr8Ob
language:
C++14 (gcc 8.3)
created:
3 days ago
visibility:
public

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