C :

#include<stdio.h>
#include<stdlib.h>
int f[2000001];
int i,j,n,k;
int cost[51];
int max=0;
int min(int u,int u1)
{
    if(u<u1) return u;
    else return u1;
}
int main()
{
    scanf("%d %d",&k,&n);
    int i;   
   
    for(i=1;i<=n;i++)
    {
      scanf("%d",&cost[i]);
      if(cost[i]>max) 
       max=cost[i];
       f[cost[i]]=1;
    } 
    for(i=1;i<=max*k+3;i++)  
      if(f[i]==0)f[i]=327676767;
    for(i=1;i<=max*k+3;i++)
      for(j=1;j<=n;j++)
       if(i-cost[j]>=1)
        f[i]=min(f[i],f[i-cost[j]]+1);
    int ans=0,sum=0;
    while(f[ans+1]<=k)
       ans++;
  printf("%d\n",ans);
 return 0;
}

C++ :

#include<stdio.h>
#include<string.h>
int dp[2001000];
int min(int x,int y)
{
	return x<y?x:y;	
}
int main()
{
		int n,k,i,j,a[100];
		scanf("%d%d",&k,&n);
		memset(dp,0,sizeof(dp));
		for (i=0;i<n;i++)	
		{
			scanf("%d",&a[i]);
			dp[a[i]]=1;	
		}
		for (i=1;;i++)
		{
			if (dp[i]!=0) continue;
			dp[i]=300;
			for (j=0;j<n;j++)
			{
				if (a[j]<i)
				dp[i]=min(dp[i],dp[i-a[j]]+1);	
			}
			if (dp[i]>k)	break;	
		}
		printf("%d",i-1);
		return 0;
}