Submission #171697

#	Time	Username	Problem	Language	Result	Execution time	Memory
171697		balbit	Tents (JOI18_tents)	C++14	100 / 100	134 ms	71008 KiB

tents

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define ull unsigned ll
#define f first
#define s second
#define FOR(i,a,b) for (int i=(a); i<(b); ++i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) for (int i=(n-1); i>=0; --i)
#define REP1(i,n) FOR(i,1,n+1)
#define ALL(x) x.begin(),x.end()
#define SZ(x) (int)x.size()
#define SQ(x) (x)*(x)
#define MN(a,b) a = min(a,(__typeof__(a))(b))
#define MX(a,b) a = max(a,(__typeof__(a))(b))
#define pb push_back
#define SORT_UNIQUE(c) (sort(c.begin(),c.end()), c.resize(distance(c.begin(),unique(c.begin(),c.end()))))
#ifdef BALBIT
#define IOS()
#define bug(...) fprintf(stderr,"#%d (%s) = ",__LINE__,#__VA_ARGS__),_do(__VA_ARGS__);
template<typename T> void _do(T &&x){cerr<<x<<endl;}
template<typename T, typename ...S> void _do(T &&x, S &&...y){cerr<<x<<", ";_do(y...);}
#else
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'
#define bug(...)
#endif

const int iinf = 1<<29;
const ll inf = 1ll<<60;
const ll mod = 1e9+7;


void GG(){cout<<"-1\n"; exit(0);}

ll mpow(ll a, ll n, ll mo = mod){ // a^n % mod
    ll re=1;
    while (n>0){
        if (n&1) re = re*a %mo;
        a = a*a %mo;
        n>>=1;
    }
    return re;
}

ll inv (ll b, ll mo = mod){
    if (b==1) return b;
    return (mo-mo/b) * inv(mo%b) % mo;
}

const int maxn = 3005;

ll dp[maxn][maxn];

main(){
    IOS();
    int n, m; cin>>n>>m;
    REP(i,n+1) REP(j,m+1) dp[i][j] = 1;
    REP1(i,n) REP1(j,m) {
        dp[i][j] = dp[i-1][j] + 4 * j * dp[i-1][j-1]%mod + (j>1?j*(j-1)/2*dp[i-1][j-2]:0)%mod + (i>1?dp[i-2][j-1] * (i-1) * j:0)%mod;
        dp[i][j] %= mod;
    }
    cout<<(dp[n][m]+mod-1)%mod<<endl;

}

Compilation message (stderr)

tents.cpp:56:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52