Knapsack Problem

struct item
{
    int val, wh;
};

int knapsack(int W, std::vector<item> V)
{
    std::vector<std::vector<int> > DP(2, std::vector<int>(W + 1, 0));

    for (int i = 1; i <= V.size(); i++)
    {
        for (int w = 1; w <= W; w++)
            if(V[i - 1].wh <= w)
                DP[1][w] = (V[i - 1].wh <= w ? std::max(V[i - 1].val + DP[0][w - V[i - 1].wh], DP[0][w])
                                             : DP[0][w]);

        std::swap(DP[0], DP[1]);
    }

    return DP[0][W];
}