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Knapsack.cpp
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Knapsack.cpp
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Copyright (c) 2021, 9mpd
All rights reserved.
This source code is licensed under the BSD-style license found in the
LICENSE file in the root directory of this source tree.
// Implementation of Fractional Knapsack Problem.
#include <iostream>
#include <vector>
#include <algorithm> // sort().
#include <iterator>
using namespace std;
bool comparator(const pair<int, float> &a,
const pair<int, float> &b)
{
return (a.second > b.second);
}
int main()
{
int n; // Number of datasets.
float c, wtx, ptx; // c is size of knapsack.
vector<float> wt, pt;
vector<pair<int, float> >vec;
cout<<"Enter the size of your Knapsack : ";
cin>>c;
cout<<"Enter the size of your dataset : ";
cin>>n;
for(int i = 0; i < n; i++)
{
cout<<"Enter the weight and profit, respectively, of "<<i+1<<"th element of the dataset :"<<endl;
cin>>wtx>>ptx;
wt.push_back(wtx);
pt.push_back(ptx);
vec.push_back(make_pair(i, (pt.at(i)/wt.at(i)) ) );
}
sort(vec.begin(), vec.end(), comparator);
int i = 0;
float profit = 0, weight = 0;
vector<float> fraction_x;
while(weight < c)
{
if(weight + wt.at(vec[i].first) <= c)
{
fraction_x.push_back(1); //Placing the complete element in the knapsack.
weight = weight + wt.at(vec[i].first);
}
else
{
float lastfill = (c - weight)/(wt.at(vec[i].first));
fraction_x.push_back(lastfill); //Placing only a fraction of element
weight = c;
}
profit = profit + pt.at(vec[i].first)*fraction_x.at(i); // Calculating the total profit.
i++;
}
cout<<"Maximum profit for the given Knapsack is "<<profit<<endl;
return 0;
}