瞎JB逆

P为质

 1 const int mod = 1000000009;  
 2 long long quickpow(long long a, long long b) {  
 3     if (b < 0) return 0;  
 4     long long ret = 1;  
 5     a %= mod;  
 6     while(b) {  
 7         if (b & 1) ret = (ret * a) % mod;  
 8         b >>= 1;  
 9         a = (a * a) % mod;  
10     }  
11     return ret;  
12 }  
13 long long inv(long long a) {  
14     return quickpow(a, mod - 2);  
15 }
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N，P互质

 1 ll extend_gcd(ll a, ll b, ll &x, ll &y) {  
 2     if (b == 0) {  
 3         x = 1, y = 0;  
 4         return a;  
 5     }  
 6     else {  
 7         ll r = extend_gcd(b, a % b, y, x);  
 8         y -= x * (a / b);  
 9         return r;  
10     }  
11 }  
12 ll inv(ll a, ll n) {  
13     ll x, y;  
14     extend_gcd(a, n, x, y);  
15     x = (x % n + n) % n;  
16     return x;  
17 }
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逆元筛

1 const int mod = 1000000009;  
2 const int maxn = 10005;  
3 int inv[maxn];  
4 inv[1] = 1;  
5 for(int i = 2; i < 10000; i++)  
6     inv[i] = inv[mod % i] * (mod - mod / i) % mod;
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阶乘逆元筛(阶乘数组：fac[ ])

1 fac[0]=fac[1]=1;
2 
3 for(int i=2;i<=MAXN;i++)fac[i]=fac[i-1]*i%mod;
4 
5 inv[MAXN]=quipow(fac[MAXN],mod-2);
6 
7 for(int i=MAXN-1;i>=0;i--)inv[i]=inv[i+1]*(i+1)%mod;
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posted @ 2018-03-04 17:20  Aragaki  阅读(135)  评论(0)  编辑  收藏  举报