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78 lines
3.3 KiB
C++
78 lines
3.3 KiB
C++
/*This is a C++ Program to solve fractional knapsack. The knapsack problem or rucksack problem is a problem in combinatorial optimization: Given a set of items, each with a mass and a value, determine the number of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible. It derives its name from the problem faced by someone who is constrained by a fixed-size knapsack and must fill it with the most valuable items.*/
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/* program to implement fractional knapsack problem using greedy programming */
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#include<iostream>
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using namespace std;
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int main()
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{
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int array[2][100], n, w, i, curw, used[100], maxi = -1, totalprofit = 0;
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//input number of objects
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cout << "Enter number of objects: ";
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cin >> n;
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//input max weight of knapsack
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cout << "Enter the weight of the knapsack: ";
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cin >> w;
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/* Array's first row is to store weights
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second row is to store profits */
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for (i = 0; i < n; i++)
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{
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cin >> array[0][i] >> array[1][i];
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}
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for (i = 0; i < n; i++)
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{
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used[i] = 0;
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}
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curw = w;
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//loop until knapsack is full
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while (curw >= 0)
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{
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maxi = -1;
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//loop to find max profit object
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for (i = 0; i < n; i++)
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{
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if ((used[i] == 0) && ((maxi == -1) || (((float) array[1][i]
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/ (float) array[0][i]) > ((float) array[1][maxi]
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/ (float) array[0][maxi]))))
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{
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maxi = i;
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}
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}
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used[maxi] = 1;
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//decrease current wight
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curw -= array[0][maxi];
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//increase total profit
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totalprofit += array[1][maxi];
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if (curw >= 0)
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{
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cout << "\nAdded object " << maxi + 1 << " Weight: "
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<< array[0][maxi] << " Profit: " << array[1][maxi]
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<< " completely in the bag, Space left: " << curw;
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}
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else
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{
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cout << "\nAdded object " << maxi + 1 << " Weight: "
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<< (array[0][maxi] + curw) << " Profit: "
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<< (array[1][maxi] / array[0][maxi]) * (array[0][maxi]
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+ curw) << " partially in the bag, Space left: 0"
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<< " Weight added is: " << curw + array[0][maxi];
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totalprofit -= array[1][maxi];
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totalprofit += ((array[1][maxi] / array[0][maxi]) * (array[0][maxi]
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+ curw));
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}
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}
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//print total worth of objects filled in knapsack
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cout << "\nBags filled with objects worth: " << totalprofit;
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return 0;
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}
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/*
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Enter number of objects: 3
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Enter the weight of the knapsack: 50
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10 60
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20 100
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30 120
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Added object 1 Weight: 10 Profit: 60 completely in the bag, Space left: 40
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Added object 2 Weight: 20 Profit: 100 completely in the bag, Space left: 20
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Added object 3 Weight: 20 Profit: 80 partially in the bag, Space left: 0 Weight added is: 20
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Bags filled with objects worth: 240
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