尝试过 Knap snap 问题，但它不起作用

如何解决尝试过 Knap snap 问题，但它不起作用

#include<stdio.h>
int max(int a,int b)
{
    if(a>b)
    return a;
    return b;
}
void knacksnap(int n,int a[][n+1],int* val,int* weight,int maxweight)
{
    if(n==0 || maxweight==0)
    {
        a[maxweight][n]=0;
        return;
    }
    if(a[maxweight][n]!=-1)
    return;
    if(weight[n-1]>maxweight)
    {
        knacksnap(n-1,a,val,weight,maxweight);
        a[maxweight][n]=a[maxweight][n-1];
    }
    else
    {
        knacksnap(n-1,maxweight-weight[n-1]);
        knacksnap(n-1,maxweight);
        a[maxweight][n]=max(val[n-1]+a[maxweight-weight[n-1]][n-1],a[maxweight][n-1]);
    }
}
int main()
{
    int n;
    scanf("%d",&n);
    int val[n],weight[n];
    int i;
    for(i=0;i<n;i++)
    scanf("%d",&val[i]);
    for(i=0;i<n;i++)
    scanf("%d",&weight[i]);
    int maxweight;
    scanf("%d",&maxweight);
    int a[maxweight+1][n+1];
    int j;
    for(i=0;i<maxweight+1;i++)
    {
        for(j=0;j<n+1;j++)
        {
            a[i][j]=-1;
        }
    }
    knacksnap(n,maxweight);
    printf("\n");
    printf("%d",a[maxweight][n]);
}

它不会通过 knacksnap 函数获取更新的值。例如，内部 knacksnap 函数没有生成正确的值。即使它们的值被更新，它也不会接受它们。有人可以帮忙吗