our happy ending(状压dp）

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
typedef long long ll;
const int mod=1e9+7;
ll dp[1<<20],ans;
int n,k,l,t,ma;
int main(){
    scanf("%d",&t);
    while(t--){
        scanf("%d%d%d",&n,&k,&l);
        memset(dp,0,sizeof(dp));
        ma=(1<<k)-1;dp[0]=1;
        for(int i=1;i<=n;++i)
          for(int j=ma;j>=0;--j)if(dp[j]){
             ll pu=dp[j];
             for(int p=1;p<=min(k,l);++p) {
                int x=(1<<p-1)|j|((j<<p)&ma);
                dp[x]+=pu;
                if(dp[x]>mod)dp[x]-=mod;
            }
            if(l>k){
                dp[j]+=(pu*(l-k))%mod;
                if(dp[j]>mod)dp[j]-=mod;
            }
        }ans=0;
        for(int i=1;i<=ma;++i)if(i&(1<<k-1)){ans+=dp[i];if(ans>mod)ans-=mod;}
        printf("%lld\n",ans);
    }
    return 0;
}