Submission #172808

#	Time	Username	Problem	Language	Result	Execution time	Memory
172808		Akashi	Tents (JOI18_tents)	C++14	100 / 100	125 ms	35672 KiB

tents

#include <bits/stdc++.h>
using namespace std;

const int MOD = 1e9 + 7;

int n, m;
int d[3005][3005];

int main()
{
//    freopen("1.in", "r", stdin);

    scanf("%d%d", &n, &m);
    d[0][n] = 1;

    for(int c = 1; c <= m ; ++c){
        for(int l = 0; l <= n ; ++l){
            d[c][l] = d[c - 1][l];
            d[c][l] = (d[c][l] + 4LL * (l + 1) * d[c - 1][l + 1]) % MOD;
            d[c][l] = (d[c][l] + 1LL * (1LL * (l + 2) * (l + 1) / 2) % MOD * d[c - 1][l + 2]) % MOD;
            if(c > 1) d[c][l] = (d[c][l] + (1LL * (m - c + 1) * (l + 1)) % MOD * d[c - 2][l + 1]) % MOD;
        }
    }

    int Sol = -1;
    for(int l = 0; l <= n ; ++l)
        Sol = (Sol + d[m][l]) % MOD;
    printf("%d", Sol);

    return 0;
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~

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