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QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#654861 | #6137. Sub-cycle Graph | ucup-team5217# | WA | 126ms | 27236kb | C++23 | 1.6kb | 2024-10-18 22:36:48 | 2024-10-18 22:36:49 |
Judging History
answer
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 2e6 + 10;
const int mod = 1e9 + 7;
int fac[N], ifac[N], inv[N];
int C(int n, int m) {
if (n < m || m < 0) return 0;
return 1ll * fac[n] * ifac[m] % mod * ifac[n - m] % mod;
}
int add(int x, int y) {
return x + y >= mod ? x + y - mod : x + y;
}
int qpow(int a, int b = mod - 2) {
int res = 1;
while (b) {
if (b & 1) res = 1ll * res * a % mod;
a = 1ll * a * a % mod;
b >>= 1;
}
return res;
}
void solve() {
ll n, m;
scanf("%lld%lld", &n, &m);
if (m == 0) {
puts("1");
return;
}
if (m >= n) {
puts("0");
return ;
}
int ans = 0;
for (int i = 0; i <= n - m; ++i) {
// ans = add(ans, 1ll * ifac[i - 2 * (n - m)] * C(i + (n - m) - 1, (n - m) - 1));
ans = add(ans, 1ll * C(n - m, i) * C(m + i - 1, i - 1) % mod);
// cerr << 1ll * 1ll * C(n - m, i) * C(m + i - 1, i - 1) % mod * fac[n] % mod * qpow(qpow(2), n - m) % mod << '\n';
}
ans = 1ll * ans * fac[n] % mod;
ans = 1ll * ans * qpow(qpow(2), n - m) % mod;
ans = 1ll * ans * ifac[n - m] % mod;
printf("%d\n", ans);
}
int main() {
fac[0] = fac[1] = inv[1] = ifac[0] = ifac[1] = 1;
for (int i = 2; i <= 2000000; ++i) {
fac[i] = 1ll * fac[i - 1] * i % mod;
inv[i] = 1ll * (mod - mod / i) * inv[mod % i] % mod;
ifac[i] = 1ll * ifac[i - 1] * inv[i] % mod;
}
int T;
scanf("%d", &T);
while (T--) {
solve();
}
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 12ms
memory: 27232kb
input:
3 4 2 4 3 5 3
output:
15 12 90
result:
ok 3 number(s): "15 12 90"
Test #2:
score: -100
Wrong Answer
time: 126ms
memory: 27236kb
input:
17446 3 0 3 1 3 2 3 3 4 0 4 1 4 2 4 3 4 4 5 0 5 1 5 2 5 3 5 4 5 5 6 0 6 1 6 2 6 3 6 4 6 5 6 6 7 0 7 1 7 2 7 3 7 4 7 5 7 6 7 7 8 0 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 9 0 9 1 9 2 9 3 9 4 9 5 9 6 9 7 9 8 9 9 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 10 9 10 10 11 0 11 1 11 2 11 3 11 4 11 5 11 6 11 7 11...
output:
1 3 3 0 1 6 15 12 0 1 10 45 90 60 0 1 15 105 375 630 360 0 1 21 210 1155 3465 5040 2520 0 1 28 378 2940 13545 35280 45360 20160 0 1 36 630 6552 42525 170100 393120 453600 181440 0 1 45 990 13230 114345 643545 2286900 4762800 4989600 1814400 0 1 55 1485 24750 273735 2047815 10239075 32848200 62370000...
result:
wrong answer 4th numbers differ - expected: '1', found: '0'