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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 |
---|---|---|---|---|---|---|---|---|---|
#226212 | #5406. 随机游走 | chenxinyang2006 | 70 | 30ms | 15688kb | C++14 | 3.8kb | 2023-10-25 18:26:21 | 2023-10-25 18:26:22 |
Judging History
answer
#include <bits/stdc++.h>
#define rep(i,j,k) for(int i=(j);i<=(k);i++)
#define per(i,j,k) for(int i=(j);i>=(k);i--)
#define uint unsigned int
#define ll long long
#define ull unsigned long long
#define db double
#define ldb long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define mkp make_pair
#define eb emplace_back
#define SZ(S) (int)S.size()
//#define mod 998244353
#define mod 1000000007
#define inf 0x3f3f3f3f
#define linf 0x3f3f3f3f3f3f3f3f
using namespace std;
template <class T>
void chkmax(T &x,T y){
if(x < y) x = y;
}
template <class T>
void chkmin(T &x,T y){
if(x > y) x = y;
}
inline int popcnt(int x){
return __builtin_popcount(x);
}
inline int ctz(int x){
return __builtin_ctz(x);
}
template <int P>
class mod_int
{
using Z = mod_int;
private:
static int mo(int x) { return x < 0 ? x + P : x; }
public:
int x;
int val() const { return x; }
mod_int() : x(0) {}
template <class T>
mod_int(const T &x_) : x(x_ >= 0 && x_ < P ? static_cast<int>(x_) : mo(static_cast<int>(x_ % P))) {}
bool operator==(const Z &rhs) const { return x == rhs.x; }
bool operator!=(const Z &rhs) const { return x != rhs.x; }
Z operator-() const { return Z(x ? P - x : 0); }
Z pow(long long k) const
{
Z res = 1, t = *this;
while (k)
{
if (k & 1)
res *= t;
if (k >>= 1)
t *= t;
}
return res;
}
Z &operator++()
{
x < P - 1 ? ++x : x = 0;
return *this;
}
Z &operator--()
{
x ? --x : x = P - 1;
return *this;
}
Z operator++(int)
{
Z ret = x;
x < P - 1 ? ++x : x = 0;
return ret;
}
Z operator--(int)
{
Z ret = x;
x ? --x : x = P - 1;
return ret;
}
Z inv() const { return pow(P - 2); }
Z &operator+=(const Z &rhs)
{
(x += rhs.x) >= P && (x -= P);
return *this;
}
Z &operator-=(const Z &rhs)
{
(x -= rhs.x) < 0 && (x += P);
return *this;
}
Z operator-()
{
return -x;
}
Z &operator*=(const Z &rhs)
{
x = 1ULL * x * rhs.x % P;
return *this;
}
Z &operator/=(const Z &rhs) { return *this *= rhs.inv(); }
#define setO(T, o) \
friend T operator o(const Z &lhs, const Z &rhs) \
{ \
Z res = lhs; \
return res o## = rhs; \
}
setO(Z, +) setO(Z, -) setO(Z, *) setO(Z, /)
#undef setO
friend istream& operator>>(istream& is, mod_int& x)
{
long long tmp;
is >> tmp;
x = tmp;
return is;
}
friend ostream& operator<<(ostream& os, const mod_int& x)
{
os << x.val();
return os;
}
};
using Z = mod_int<mod>;
Z power(Z p,ll k){
Z ans = 1;
while(k){
if(k % 2 == 1) ans *= p;
p *= p;
k /= 2;
}
return ans;
}
Z fact[1000005],ifac[1000005],inv[1000005];
Z C(int N,int M){
if(N < M || M < 0) return 0;
return fact[N] * ifac[M] * ifac[N - M];
}
void init(int L){
fact[0] = 1;
rep(i,1,L) fact[i] = fact[i - 1] * i;
ifac[L] = 1 / fact[L];
per(i,L - 1,0) ifac[i] = ifac[i + 1] * (i + 1);
rep(i,1,L) inv[i] = ifac[i] * fact[i - 1];
}
int n;
int main(){
scanf("%d",&n);
init(2 * n);
Z ans = 0,temp;
rep(i,0,n){
temp = C(2 * n,i) * power(n - i,2 * n + 1);
if(i % 2) ans -= temp;
else ans += temp;
}
ans /= 2 * n + 1;
ans /= fact[2 * n];
ans *= 2;
printf("%d\n",ans.val());
return 0;
}
详细
Subtask #1:
score: 5
Accepted
Test #1:
score: 5
Accepted
time: 3ms
memory: 15548kb
input:
1
output:
333333336
result:
ok 1 number(s): "333333336"
Test #2:
score: 0
Accepted
time: 0ms
memory: 15500kb
input:
2
output:
266666669
result:
ok 1 number(s): "266666669"
Test #3:
score: 0
Accepted
time: 0ms
memory: 15648kb
input:
3
output:
769047625
result:
ok 1 number(s): "769047625"
Subtask #2:
score: 10
Accepted
Test #4:
score: 10
Accepted
time: 0ms
memory: 15632kb
input:
4
output:
877865968
result:
ok 1 number(s): "877865968"
Test #5:
score: 0
Accepted
time: 2ms
memory: 15564kb
input:
5
output:
733342859
result:
ok 1 number(s): "733342859"
Test #6:
score: 0
Accepted
time: 2ms
memory: 15584kb
input:
6
output:
655899114
result:
ok 1 number(s): "655899114"
Test #7:
score: 0
Accepted
time: 3ms
memory: 15644kb
input:
7
output:
946326757
result:
ok 1 number(s): "946326757"
Test #8:
score: 0
Accepted
time: 0ms
memory: 15648kb
input:
8
output:
230714822
result:
ok 1 number(s): "230714822"
Test #9:
score: 0
Accepted
time: 3ms
memory: 15632kb
input:
9
output:
782967541
result:
ok 1 number(s): "782967541"
Test #10:
score: 0
Accepted
time: 0ms
memory: 15556kb
input:
10
output:
732371611
result:
ok 1 number(s): "732371611"
Subtask #3:
score: 10
Accepted
Test #11:
score: 10
Accepted
time: 2ms
memory: 15684kb
input:
15
output:
677123472
result:
ok 1 number(s): "677123472"
Test #12:
score: 0
Accepted
time: 0ms
memory: 15644kb
input:
13
output:
168974634
result:
ok 1 number(s): "168974634"
Test #13:
score: 0
Accepted
time: 2ms
memory: 15548kb
input:
26
output:
213343876
result:
ok 1 number(s): "213343876"
Test #14:
score: 0
Accepted
time: 2ms
memory: 15684kb
input:
29
output:
631124616
result:
ok 1 number(s): "631124616"
Subtask #4:
score: 15
Accepted
Test #15:
score: 15
Accepted
time: 2ms
memory: 15644kb
input:
37
output:
349256161
result:
ok 1 number(s): "349256161"
Test #16:
score: 0
Accepted
time: 2ms
memory: 15648kb
input:
104
output:
351095881
result:
ok 1 number(s): "351095881"
Test #17:
score: 0
Accepted
time: 0ms
memory: 15500kb
input:
194
output:
895504391
result:
ok 1 number(s): "895504391"
Test #18:
score: 0
Accepted
time: 3ms
memory: 15564kb
input:
197
output:
923555376
result:
ok 1 number(s): "923555376"
Test #19:
score: 0
Accepted
time: 0ms
memory: 15620kb
input:
198
output:
512220517
result:
ok 1 number(s): "512220517"
Subtask #5:
score: 15
Accepted
Test #20:
score: 15
Accepted
time: 3ms
memory: 15560kb
input:
562
output:
255062346
result:
ok 1 number(s): "255062346"
Test #21:
score: 0
Accepted
time: 0ms
memory: 15584kb
input:
1007
output:
735041605
result:
ok 1 number(s): "735041605"
Test #22:
score: 0
Accepted
time: 2ms
memory: 15628kb
input:
1788
output:
208261384
result:
ok 1 number(s): "208261384"
Test #23:
score: 0
Accepted
time: 0ms
memory: 15644kb
input:
1980
output:
875427987
result:
ok 1 number(s): "875427987"
Test #24:
score: 0
Accepted
time: 0ms
memory: 15560kb
input:
1983
output:
571776252
result:
ok 1 number(s): "571776252"
Test #25:
score: 0
Accepted
time: 0ms
memory: 15504kb
input:
1992
output:
12983695
result:
ok 1 number(s): "12983695"
Subtask #6:
score: 15
Accepted
Test #26:
score: 15
Accepted
time: 2ms
memory: 15676kb
input:
3946
output:
977435333
result:
ok 1 number(s): "977435333"
Test #27:
score: 0
Accepted
time: 4ms
memory: 15640kb
input:
65944
output:
312666196
result:
ok 1 number(s): "312666196"
Test #28:
score: 0
Accepted
time: 17ms
memory: 15624kb
input:
163815
output:
163767254
result:
ok 1 number(s): "163767254"
Test #29:
score: 0
Accepted
time: 15ms
memory: 15636kb
input:
198732
output:
911833524
result:
ok 1 number(s): "911833524"
Test #30:
score: 0
Accepted
time: 19ms
memory: 15632kb
input:
199287
output:
910277128
result:
ok 1 number(s): "910277128"
Test #31:
score: 0
Accepted
time: 15ms
memory: 15636kb
input:
199819
output:
561747634
result:
ok 1 number(s): "561747634"
Subtask #7:
score: 0
Runtime Error
Test #32:
score: 30
Accepted
time: 30ms
memory: 15688kb
input:
315618
output:
602805814
result:
ok 1 number(s): "602805814"
Test #33:
score: -30
Runtime Error
input:
1130465