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Fractional Knapsack

Sumit Rawal answered on February 6, 2022 Popularity 9/10 Helpfulness 1/10

answer Fractional Knapsack

Fractional Knapsack

Comment

/*
class Item {
    int value, weight;
    Item(int x, int y){
        this.value = x;
        this.weight = y;
    }
}
*/

class CompareElements implements Comparator<Item>
{
    @Override
    public int compare(Item a, Item b)
    {
        double val1= (double)a.value/a.weight;
        double val2= (double)b.value/b.weight;
        
        if(val1>val2)
        return -1;
        
        else if(val2>val1)
        return 1;
        
        else
        return 0;
    }
}

class Solution
{
    //Function to get the maximum total value in the knapsack.
    double fractionalKnapsack(int W, Item arr[], int n) 
    {
        Arrays.sort(arr, new CompareElements());
        
        double currentValue=0;
        
        for(int i = 0 ; i<n;i++)
        {
            if(arr[i].weight<=W)
            {
                currentValue+=arr[i].value;
                W-=arr[i].weight;
            }
            else
            {
                currentValue+= ((double)arr[i].value/(double)arr[i].weight)*(double)W;
                break;
            }
        }
        return currentValue;
    }
}

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Contributed on Oct 19 2022

Sumit Rawal

0 Answers Avg Quality 2/10

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Fractional Knapsack problem

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#include<bits/stdc++.h>
using namespace std;

float p[100],w[100];
float x[100];

    void knapsack(int m,int n)
    {
        for(int i = 1; i<n; i++)
        {
            int maX = i;
            for(int j =i+1;j<=n;j++)
            {
                if(p[j]/w[j] > p[maX]/w[maX])
                {
                    maX = j;
                }
            }
            swap(p[maX],p[i]);
            swap(w[maX],w[i]);

        }

        int u = m;
        int i;
        for(i=1;i<=n;i++)
        {
            if(w[i]>u)
                break;
            x[i] = 1;
            u = u-w[i];
        }
        if(i<=n)
        {
            x[i] = u/w[i];
        }
    }


    void profit_calculation(int n)
    {
        float sum = 0;
        for(int i = 1;i<=n;i++)
            sum += x[i]*p[i];
        cout<<sum;
    }


int main()
{

   int n;    // n is the number of items
    cout<<"Enter the no. of items:";
    cin>>n;
    for(int i = 1;i<=n;i++)
    {
        cin>>p[i]>>w[i];  // Enter Profit space Weight respectively

    }
    cout<<endl;
    knapsack(60,4);
    cout<<"After Sorting according to unit profit: "<<endl;
    cout<<"profit: ";
    for(int i = 1;i<=n;i++)
        cout<<p[i]<<" ";
    cout<<endl<<"Weight: ";
    for(int i = 1;i<=n;i++)
        cout<<w[i]<<" ";
    cout<<endl;

    cout<<"You can take the items respectively portion of:"<<endl;
    for(int i = 1;i<=n;i++)
        cout<<x[i]<<" ";
    cout<<endl;
    cout<<"your total profit is: ";
    profit_calculation(n);



    return 0;
}

Popularity 10/10 Helpfulness 2/10 Language cpp

Source: paste.ubuntu.com

Tags: c++

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Contributed on Feb 06 2022

Depressed Dragonfly

0 Answers Avg Quality 2/10

fractional knapsack

Comment

# Structure for an item which stores weight and
# corresponding value of Item
class Item:
    def __init__(self, value, weight):
        self.value = value
        self.weight = weight
    def __repr__(self): 
        return " value:% s weight:% s" % (self.value, self.weight) #used to print THE CLASSES LISTS
# Main greedy function to solve problem
def fractionalKnapsack(W, arr):
 
    # sorting Item on basis of ratio
    arr.sort(key=lambda x: (x.value/x.weight), reverse=True)
 
    # Uncomment to see new order of Items with their
    # ratio
    # for item in arr:
    #     print(item.value, item.weight, item.value/item.weight)
 
    # Result(value in Knapsack)
    finalvalue = 0.0
 
    # Looping through all Items
    for item in arr:
 
        # If adding Item won't overflow, add it completely
        if item.weight <= W:
            W -= item.weight
            finalvalue += item.value
 
        # If we can't add current Item, add fractional part
        # of it
        else:
            finalvalue += item.value * W / item.weight
            break
    # Returning final value
    return finalvalue
import random
import matplotlib.pyplot as plt
import time
timeList=[]
fornnumberList=[]
for i in range(6):
    no=random.choice(range(6))
    numList=random.sample(range(10,100,5),no)#for 'no' random numbers 
    num=random.choice(numList) #used for weights
    print("Limit Weight",num)
    numpList=random.sample(range(10,100,6),no)
    #nump=random.choice(numpList) #num and nump instead of here if used in function each time a new number shows up
    start_time=time.time()
    arrayList=[]
    for i in range(no):
        arrayList.append(Item(random.choice(numpList),random.choice(numList)))
    print(arrayList)
    fractionalKnapsack(num,arrayList)#enter the function here
    print("knapsack value",fractionalKnapsack(num,arrayList))
    end_time=time.time()
    final_time= end_time- start_time
    timeList.append(final_time)
    fornnumberList.append(no)
x=timeList
y=fornnumberList
plt.xlabel("Time taken")
plt.ylabel("For 'x' random numbers")
plt.plot(x, y)
plt.scatter(x,y)

Popularity 9/10 Helpfulness 1/10 Language python

Source: Grepper

Tags: python py

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Contributed on Nov 29 2022

Horrible Heron

0 Answers Avg Quality 2/10

Fractional Knapsack

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fractional knapsack

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