1. 程式人生 > >BZOJ4591 SHOI2015超能粒子炮·改(盧卡斯定理+數位dp)

BZOJ4591 SHOI2015超能粒子炮·改(盧卡斯定理+數位dp)

  注意到模數很小,容易想到使用盧卡斯定理,即變成一個2333進位制數各位組合數的乘積。對於k的限制容易想到數位dp。可以預處理一發2333以內的組合數及組合數字首和,然後設f[i][0/1]為前i位是否卡限制的貢獻就很好dp了。為什麼大家都要化式子呢。

#include<iostream> 
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
#define
ll long long #define P 2333 ll read() { ll x=0,f=1;char c=getchar(); while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();} while (c>='0'&&c<='9') x=(x<<1)+(x<<3)+(c^48),c=getchar(); return x*f; } char getc(){char c=getchar();while ((c<'A'||c>'Z')&&(c<'
a'||c>'z')) c=getchar();return c;} int gcd(int n,int m){return m==0?n:gcd(m,n%m);} int T,C[P][P],S[P][P],a[20],b[20],f[20][2]; ll n,m; int calc(ll n,ll m) { int t=-1; while (n) a[++t]=n%P,n/=P; for (int i=0;i<=t;i++) b[i]=m%P,m/=P; memset(f,0,sizeof(f)); f[t+1][1]=1; for (int i=t;~i;i--) { f[i][
1]=f[i+1][1]*C[a[i]][b[i]]%P; if (b[i]) f[i][0]=f[i+1][1]*S[a[i]][b[i]-1]%P; f[i][0]=(f[i][0]+f[i+1][0]*S[a[i]][P-1]%P)%P; } return (f[0][0]+f[0][1])%P; } int main() { #ifndef ONLINE_JUDGE freopen("bzoj4591.in","r",stdin); freopen("bzoj4591.out","w",stdout); const char LL[]="%I64d\n"; #else const char LL[]="%lld\n"; #endif T=read(); for (int i=0;i<P;i++) { C[i][0]=C[i][i]=1; for (int j=1;j<i;j++) C[i][j]=(C[i-1][j-1]+C[i-1][j])%P; S[i][0]=1; for (int j=1;j<P;j++) S[i][j]=(S[i][j-1]+C[i][j])%P; } while (T--) { n=read(),m=min(n,read()); printf("%d\n",calc(n,m)); } return 0; }