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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#810653 | #6137. Sub-cycle Graph | Sktn0089 | AC ✓ | 71ms | 10336kb | C++14 | 2.1kb | 2024-12-12 08:01:32 | 2024-12-12 08:01:33 |
Judging History
answer
#include <bits/stdc++.h>
namespace Initial {
#define ll long long
#define ull unsigned long long
#define fi first
#define se second
#define mkp make_pair
#define pir pair <int, int>
#define pb emplace_back
#define i128 __int128
using namespace std;
const ll maxn = 2e5 + 10, inf = 1e9, mod = 1e9 + 7;
ll power(ll a, ll b = mod - 2) {
ll s = 1;
while(b) {
if(b & 1) s = 1ll * s * a %mod;
a = 1ll * a * a %mod, b >>= 1;
} return s;
}
template <class T>
const inline ll pls(const T x, const T y) { return x + y >= mod? x + y - mod : x + y; }
template <class T>
const inline void add(T &x, const T y) { x = x + y >= mod? x + y - mod : x + y; }
template <class T>
const inline void chkmax(T &x, const T y) { x = x < y? y : x; }
template <class T>
const inline void chkmin(T &x, const T y) { x = x > y? y : x; }
} using namespace Initial;
namespace Read {
char buf[1 << 22], *p1, *p2;
// #define getchar() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, (1 << 22) - 10, stdin), p1 == p2)? EOF : *p1++)
template <class T>
const inline void rd(T &x) {
char ch; bool neg = 0;
while(!isdigit(ch = getchar()))
if(ch == '-') neg = 1;
x = ch - '0';
while(isdigit(ch = getchar()))
x = (x << 1) + (x << 3) + ch - '0';
if(neg) x = -x;
}
} using Read::rd;
ll t, n, m, fac[maxn], ifac[maxn], N = 2e5, pw[maxn];
signed main() {
rd(t), fac[0] = pw[0] = 1;
for(ll i = 1; i <= N; i++)
fac[i] = fac[i - 1] * i %mod, pw[i] = pw[i - 1] * (mod - mod / 2) %mod;
ifac[N] = power(fac[N]);
for(ll i = N; i; i--) ifac[i - 1] = ifac[i] * i %mod;
while(t--) {
rd(n), rd(m);
if(m > n) puts("0");
else if(m == n) printf("%lld\n", (mod - mod / 2) * fac[n - 1] %mod);
else {
ll ans = 0; m = n - m;
for(ll i = 0; i <= m; i++) {
ll now = n - m - i;
if(!i) add(ans, (!now) * ifac[m]);
else if(now >= 0)
add(ans, ifac[i] * ifac[m - i] %mod * ifac[i - 1] %mod * ifac[now]
%mod * fac[i - 1 + now] %mod * pw[i] %mod);
} printf("%lld\n", ans * fac[n] %mod);
}
}
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 4ms
memory: 10336kb
input:
3 4 2 4 3 5 3
output:
15 12 90
result:
ok 3 number(s): "15 12 90"
Test #2:
score: 0
Accepted
time: 71ms
memory: 10172kb
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 1 1 6 15 12 3 1 10 45 90 60 12 1 15 105 375 630 360 60 1 21 210 1155 3465 5040 2520 360 1 28 378 2940 13545 35280 45360 20160 2520 1 36 630 6552 42525 170100 393120 453600 181440 20160 1 45 990 13230 114345 643545 2286900 4762800 4989600 1814400 181440 1 55 1485 24750 273735 2047815 10239075 3...
result:
ok 17446 numbers