UVa 357 Let Me Count The Ways

// aarifshuvo   ``CSEJU

#include <bits/stdc++.h>
#define ll long long
#define SZ(x) ((int)(x).size())
#define scl(x) scanf("%lld", &x)
#define scll(x,y) scanf("%lld %lld", &x, &y)
#define ALL(x) (x).begin(),(x).end()
#define REP(i,n) for(int i=0;i<n;i++)
#define REV(i,n) for(int i=n-1;i>=0;i--)
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define pri(a) cout<<a<<endl
#define prii(a,b) cout<<a<<" "<<b<<endl
using namespace std;

ll n, mem[6][31000];
ll coins[] = {1, 5, 10, 25, 50};

ll call(ll i, ll feas)
{
    if(feas==0) return 1;
    if(i==5) return 0;

    if(mem[i][feas]!=-1) return mem[i][feas];

    mem[i][feas] = 0;

    for(int j=0; feas-coins[i]*j>=0; j++)
    {
        mem[i][feas] += call(i+1, feas-coins[i]*j);
    }
    return mem[i][feas];
}

int main()
{
    memset(mem,-1,sizeof mem);
    while(~scl(n))
    {
        ll res = call(0,n);
        if(res==1)
            printf("There is only 1 way to produce %lld cents change.\n", n);
        else
            printf("There are %lld ways to produce %lld cents change.\n", res, n);
    }
    return 0;
}