Knapsack se aproveitando de C++11

knapsack.cpp

#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;

const int N = (2e3) + 7;
int n, k, w[N], v[N];
int _S[N][N];
int& S(int i, int w) { return (w >= 0) ? _S[i][w] : _S[N-1][N-1]; }
int s(int i, int w) { return max({S(i+1,w), v[i] + S(i+1,w-::w[i])}); }

int main(){
    scanf(" %d%d", &k, &n);
    S(N-1,N-1) = INT_MIN;
    for(int i=0;i<n;i++) scanf(" %d%d", w+i, v+i);
    for(int i=n-1;i+1;i--)
        for(int w=0;w<=k;w++)
            S(i,w) = s(i,w);
    printf("%d\n", S(0,k));
}