Submission #44485

#	Time	Username	Problem	Language	Result	Execution time	Memory
44485		imaxblue	Tents (JOI18_tents)	C++17	100 / 100	449 ms	87548 KiB

tents

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
#define pb push_back
#define x first
#define y second
#define pii pair<int, int>
#define p3i pair<pii, int>
#define pll pair<ll, ll>
#define p3l pair<pll, ll>
#define lseg L, (L+R)/2, N*2+1
#define rseg (L+R)/2+1, R, N*2+2
#define ub upper_bound
#define lb lower_bound
#define pq priority_queue
#define MN 1000000007
#define fox(k, x) for (int k=0; k<x; ++k)
#define fox1(k, x) for (int k=1; k<=x; ++k)
#define foxr(k, x) for (int k=x-1; k>=0; --k)
#define fox1r(k, x) for (int k=x; k>0; --k)
#define ms multiset
#define flood(x) memset(x, 0x3f3f3f3f, sizeof x)
#define drain(x) memset(x, 0, sizeof x)
#define rng() ((rand() << 14)+rand())
#define scan(X) do{while((X=getchar())<'0'); for(X-='0'; '0'<=(_=getchar()); X=(X<<3)+(X<<1)+_-'0');}while(0)
char _;
#define pi 3.14159265358979323846

int add(int&A, int B){
    A=(A+B)%MN;
}
int mult(int&A, int B){
    A=(1LL*A*B)%MN;
}

int n, m, ncr[3005][3005]={1}, dp[3005][3005], seqpic[3005][3005];
int solve(int X, int Y){
    if (X==0) return 1;
    if (X<0 || Y<0) return 0;
    if (dp[X][Y]!=0) return dp[X][Y];
    add(dp[X][Y], solve(X-1, Y));
    add(dp[X][Y], 4LL*solve(X-1, Y-1)*Y%MN);
    //cout << step << ' ' << X << ' ' << Y << ' ' << dp[X][Y] << endl;
    return dp[X][Y];
}
int ans, x, y, x2, y2, t, t2;
int main(){
    fox(l, 3002){
        seqpic[l][0]=1;
        fox(l2, l+1){
            add(ncr[l+1][l2], ncr[l][l2]);
            add(ncr[l+1][l2+1], ncr[l][l2]);
        }
        fox(l2, l+1){
            if (l>1 && l2>0){
                seqpic[l][l2]=seqpic[l-2][l2-1];
                mult(seqpic[l][l2], ncr[l][2]);
                //cout << seqpic[l][l2] << ' ';
            }
        }
        //cout << endl;
    }
    cin >> n >> m;
    fox(l, n+2){
        x2=n-l;
        y2=m-l*2;
        if (x2<0 || y2<0) break;
        t=ncr[n][x2];
        mult(t, seqpic[m][l]);
        fox(l2, m+2){
            x=x2-l2*2;
            y=y2-l2;
            if (x<0 || y<0) break;
            t2=t;
            mult(t2, seqpic[x2][l2]);
            mult(t2, ncr[y2][y]);
            mult(t2, solve(x, y));
            //cout << x << ' ' << y << ' ' << t2/solve(x, y) << ' ' << solve(x, y)<< endl;
            add(ans, t2);
        }
    }
    cout << (ans+MN-1)%MN;
    return 0;
}

Compilation message (stderr)

tents.cpp: In function 'int add(int&, int)':
tents.cpp:32:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
tents.cpp: In function 'int mult(int&, int)':
tents.cpp:35:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^

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