提出 #67788367

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ソースコード 拡げる

#include<bits/stdc++.h>
typedef long double ld;
typedef long long ll;
#define nl '\n'
#define vi vector<int>
#define vll vector<ll>
#define vpii vector<pair<int,int>>
#define vpll vector<pair<ll,ll>>
#define rep(i,a,b) for(int i = (a); i < (b); i++)
#define per(i,a,b) for(int i = (a); i >= (b); i--)
#define repl(i,a,b) for(ll i = (a); i < (b); i++)
#define perl(i,a,b) for(ll i = (a); i >= (b); i--)
using namespace std;
const ll MOD = 1000000007, MOD2 = 998244353, mod = MOD2;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll N=5e5+5;
ll fct[N],inv[N],invfct[N];
ll ncr(ll n,ll r){
    if(n<0 || r<0 || n-r<0)return 0;
    ll ans = fct[n]*invfct[r];
    ans%=mod;
    ans = ans * invfct[n-r];
    ans%=mod;
    return ans;
}
void init(){
    fct[0]=fct[1]=1;
    inv[1]=1;
    invfct[0]=invfct[1]=1;
    for(ll i=2;i<N;i++){
        fct[i]=i*fct[i-1]%mod;
        inv[i]=ll(mod-inv[mod%i])*(mod/i)%mod;
        invfct[i]=ll(inv[i])*invfct[i-1]%mod;
    }
}
void solve(){
    ll n,m; cin>>n>>m;
    if(n%2==0){cout<<0<<nl; return;}
    ll ans = 0;
    if(m&1){
        repl(t,0,n+1){
            ll sum = abs(t-(n-t));
            ll ways = ncr(n, t);
            if(__gcd(sum, m) == 1) ans = (ans + ways) % mod;
        }
    }
    else{
        repl(t,0,2*n+1){
            ll sum = abs((t - (2*n-t))/2);
            ll ways = ncr(2*n, t);
            if(__gcd(sum, m/2) == 1) ans = (ans + ways) % mod;
        }
    }
    cout<<ans<<nl;
}

int main(){
    ios_base:: sync_with_stdio(false);
    cin.tie(NULL);
    init();
    //int __; cin>>__; while(__--) solve();
    solve();
    return 0;
}

提出情報

ジャッジ結果