Submission #838707

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Source Code Expand

#include <bits/stdc++.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using namespace std;

using ll=long long;

const ll inf =1LL << 62;
const ll mod=1000000007LL;

inline ll extgcd(ll a,ll b,ll& x,ll& y){x=1,y=0;ll g=a;if(b!=0) g=extgcd(b,a%b,y,x),y-=a/b*x;return g;}
inline ll ADD(const ll &a, const ll &b,const ll &mod) { return a+b<mod?a+b:a+b-mod;}
inline ll SUB(const ll &a, const ll &b,const ll &mod) { return a-b>=0?a-b:a-b+mod;}
inline ll MUL(const ll &a, const ll &b,const ll &mod) { return (1LL*a*b)%mod;}
inline ll INV(ll a,ll mod){ll x,y;extgcd(a,mod,x,y);return (x%mod+mod)%mod;}
inline ll DIV(const ll &a, const ll &b,const ll &mod) {return MUL(a,INV(b,mod),mod);}
inline ll POW(ll a,ll n,ll mod){ll b=1LL;for(a%=mod;n;a=MUL(a,a,mod),n>>=1)if(n&1) b=MUL(b,a,mod); return b;}

ll a[410],b[410];
ll coef[410][410];
int n,c;

ll rec(ll i,ll res){
	if(i==n) return res==0;

	ll &ret=coef[i][res];
	if(ret!=-1) return ret;

	ret=0LL;
	ll cur=1LL;
	rrep(nxt,res+1){
		ll tar=MUL(cur,rec(i+1,nxt),mod);
		ret=ADD(ret,tar,mod);
		cur=MUL(cur,a[i],mod);
	}
	return ret;
}

int main(void){
	cin >> n >> c;
	rep(i,n) cin >> a[i];
	rep(i,n) cin >> b[i];

	rep(i,n)rep(j,c+1) coef[i][j]=-1;
	cout << rec(0,c) << endl;
	return 0;
}

Submission Info

Judge Result