oj.uz

Submission #101067

# Submission time Handle Problem Language Result Execution time Memory
101067 2019-03-16T08:55:07 Z ecasdqina Tents (JOI18_tents) C++14
100 / 100
 323 ms 71032 KB 
#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = long long;
using std::cout;
using std::endl;
using std::cin;
 
const int MOD = 1e9 + 7;
 
i64 mod_pow(i64 x, i64 n = MOD - 2) {
	i64 ret = 1;
	while(n) {
		if(n & 1) (ret *= x) %= MOD;
		(x *= x) %= MOD;
		n >>= 1;
	}
	return ret;
}
 
std::vector<i64> fact, inv;
i64 comb(int n, int r) {
	return fact[n] * inv[n - r] % MOD * inv[r] % MOD;
}
 
int main() {
	int h, w; scanf("%d%d", &h, &w);
	
//	assert(h <= 300 and w <= 300);
	
	fact.assign(std::max(h, w) + 1, 1); inv.assign(std::max(h, w) + 1, 1);
	for(int i = 0; i < std::max(h, w); i++) fact[i + 1] = fact[i] * (i64)(i + 1) % MOD;
	for(int i = 0; i <= std::max(h, w); i++) inv[i] = mod_pow(fact[i]);
	
	std::vector<std::vector<i64>> dp(h + 1, std::vector<i64>(w + 1, 0));
	dp[h][w] = 1;
	for(i64 i = h; i >= 0; i--) {
		for(i64 j = w; j >= 0; j--) {
			if(i >= 1 and j >= 1) {
				dp[i - 1][j - 1] += dp[i][j] * j % MOD * 4;
				dp[i - 1][j - 1] %= MOD;
			}
			if(i >= 1 and j >= 2) {
				dp[i - 1][j - 2] += dp[i][j] * comb(j, 2) % MOD;
				dp[i - 1][j - 2] %= MOD;
			}
			if(i >= 2 and j >= 1) {
				dp[i - 2][j - 1] += dp[i][j] * j % MOD * (i - 1) % MOD;
				dp[i - 2][j - 1] %= MOD;
			}
			if(i >= 1) {
				dp[i - 1][j] += dp[i][j];
				dp[i - 1][j] %= MOD;
			}
		}
	}
	
	i64 ans = 0;
	for(int j = 0; j <= w; j++) (ans += dp[0][j]) %= MOD;
	printf("%lld\n", (ans - 1 + MOD) % MOD);
	return 0;
}

Compilation message

tents.cpp: In function 'int main()':
tents.cpp:26:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int h, w; scanf("%d%d", &h, &w);
            ~~~~~^~~~~~~~~~~~~~~~

Subtask #1
48.0 / 48.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 256 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 256 KB Output is correct
4 Correct 3 ms 384 KB Output is correct
5 Correct 3 ms 384 KB Output is correct
6 Correct 3 ms 512 KB Output is correct
7 Correct 0 ms 512 KB Output is correct
8 Correct 2 ms 384 KB Output is correct
9 Correct 2 ms 384 KB Output is correct
10 Correct 4 ms 640 KB Output is correct
11 Correct 3 ms 384 KB Output is correct
12 Correct 7 ms 1024 KB Output is correct

Subtask #2
52.0 / 52.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 256 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 256 KB Output is correct
4 Correct 3 ms 384 KB Output is correct
5 Correct 3 ms 384 KB Output is correct
6 Correct 3 ms 512 KB Output is correct
7 Correct 0 ms 512 KB Output is correct
8 Correct 2 ms 384 KB Output is correct
9 Correct 2 ms 384 KB Output is correct
10 Correct 4 ms 640 KB Output is correct
11 Correct 3 ms 384 KB Output is correct
12 Correct 7 ms 1024 KB Output is correct
13 Correct 3 ms 384 KB Output is correct
14 Correct 4 ms 512 KB Output is correct
15 Correct 207 ms 44296 KB Output is correct
16 Correct 14 ms 3200 KB Output is correct
17 Correct 41 ms 10212 KB Output is correct
18 Correct 58 ms 12544 KB Output is correct
19 Correct 207 ms 51448 KB Output is correct
20 Correct 179 ms 41336 KB Output is correct
21 Correct 153 ms 27264 KB Output is correct
22 Correct 112 ms 27008 KB Output is correct
23 Correct 60 ms 15096 KB Output is correct
24 Correct 312 ms 71032 KB Output is correct
25 Correct 234 ms 52764 KB Output is correct
26 Correct 269 ms 60536 KB Output is correct
27 Correct 323 ms 68288 KB Output is correct