关于dp和记忆化搜索

/* Farewell. */
#include <iostream>
#include <vector>
#include <cstdio>
#include <stack>
#include <cstring>
#include <algorithm>
#include <queue>
#include <map>
#include <string>
#include <cmath>
#include <bitset>
#include <iomanip>
#include <set>
using namespace std;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define gcd __gcd
#define debug(x) std::cerr << #x << " = " << (x) << std::endl
typedef long long  LL;
typedef unsigned long long ULL;
typedef pair<int,int > pii;
typedef pair<LL,LL> pll;
typedef pair<double,double > pdd;
typedef pair<double,int > pdi;
const int INF = 0x7fffffff;
const LL INFF = 0x7f7f7f7fffffffff;
const int MAXM = 5e3+17;

const int MOD = 998244353;
const int MAXN = 3e3+17;
LL ans = 0;
int n,x,k,id = 0;
void dfs(int now,int be,int lft)
{
ans = (ans+1)%MOD;
if(be+1<k&&lft>=now)
{
dfs(now,be+1,lft-now);
}
//debug(lft);debug(ans);
for (int i = now+1; i <= lft ; ++i)
{
dfs(i, 1, lft-i);
// vec.pop_back();
}

}
int main(int argc, char const *argv[])
{
#ifdef GoodbyeMonkeyKing
freopen("Input.txt","r",stdin);freopen("Output.txt","w",stdout);
#endif
cin>>n>>x>>k;
for (int i = x; i <= n ; ++i)
{
//vector<int > vec;
//vec.push_back(i);
dfs(i,1,n-i);
}
cout<<ans<<endl;
return 0;
}