Submission #61963

#	Time	Username	Problem	Language	Result	Execution time	Memory
61963		gusfring	Tents (JOI18_tents)	C++14	100 / 100	1185 ms	71628 KiB

tents

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
 
int n, m;
ll dp[3010][3010], MOD = 1e9+7;

int mod(ll x){ return x % MOD; }
int main() {
  int i, j;
  scanf("%d%d",&n,&m);
  for(int i=0; i<=m; ++i) dp[0][i] = 1;
  for(int i=0; i<=n; ++i) dp[i][0] = 1;
  for(int i=1; i<=n; ++i)
		for(int j=1; j<=m; ++j){
			dp[i][j] = dp[i - 1][j];
			dp[i][j] = mod(dp[i][j] + mod(dp[i - 1][j - 1] * 4 * j));
			dp[i][j] = mod(dp[i][j] + mod(dp[i - 2][j - 1] * j * (i - 1)));
			dp[i][j] = mod(dp[i][j] + mod(dp[i - 1][j - 2] * mod(j * (j - 1) / 2)));
		}
  printf("%lld\n", (dp[n][m] - 1 + MOD) % MOD);
  return 0;
}

Compilation message (stderr)

tents.cpp: In function 'int main()':
tents.cpp:12:7: warning: unused variable 'i' [-Wunused-variable]
   int i, j;
       ^
tents.cpp:12:10: warning: unused variable 'j' [-Wunused-variable]
   int i, j;
          ^
tents.cpp:13:8: 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