0_1knapsack.cpp

// A Dynamic Programming based solution for 0-1 Knapsack problem
#include <iostream>

using namespace std;

// A utility function that returns maximum of two integers
int max(int a, int b)
{
    return (a > b) ? a : b;
}

// Returns the maximum value that can be put in a knapsack of capacity W
int knapSack(int W, int wt[], int val[], int n)
{
    int i, w;
    int K[n + 1][W + 1];

    // Build table K[][] in bottom up manner
    for (i = 0; i <= n; i++)
    {
        for (w = 0; w <= W; w++)
        {
            if (i == 0 || w == 0)
                K[i][w] = 0;
            else if (wt[i - 1] <= w)
                K[i][w]
                        = max(val[i - 1] + K[i - 1][w - wt[i - 1]], K[i - 1][w]);
            else
                K[i][w] = K[i - 1][w];
        }
    }

    return K[n][W];
}

int main()
{
    cout << "Enter the number of items in a Knapsack:";
    int n, W;
    cin >> n;
    int val[n], wt[n];
    for (int i = 0; i < n; i++)
    {
        cout << "Enter value and weight for item " << i << ":";
        cin >> val[i];
        cin >> wt[i];
    }

    //    int val[] = { 60, 100, 120 };
    //    int wt[] = { 10, 20, 30 };
    //    int W = 50;
    cout << "Enter the capacity of knapsack";
    cin >> W;
    cout << knapSack(W, wt, val, n);

    return 0;
}