java 数论板子

	static final int maxn=(int)1e6+5;
	static int mod=(int)1e9+7;
	static long []fac=new long[maxn];
	public static long _pow(long a,long t) {
		long ans=1;
		while(t>0) {
			if((t&1)==1) ans=ans*a%mod;
			a=a*a%mod;
			t>>=1;
		}
		return ans;
	}
	public static long inv(long x) {
		return _pow(x,mod-2);
	}
	public static void init() {
		fac[0]=1;
		for(int i=1;i<maxn;i++) {
			fac[i]=fac[i-1]*(long)i%mod;
		}
	}
	public static long C(int m,int i) {
		long ans=0;
		ans=fac[m]*inv(fac[m-i])%mod*inv(fac[i])%mod;
		return ans;
	}
	public static int gcd(int a,int b) {
		if(a<b) return gcd(b,a);
		if(a%b==0) 
			return b;
		return gcd(b,a%b);
	}