BZOJ1856: [Scoi2010]字符串

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<iostream>
 7 #include<vector>
 8 #include<map>
 9 #include<set>
10 #include<queue>
11 #include<string>
12 #define inf 1000000000
13 #define maxn 1000000+1000
14 #define maxm 500+100
15 #define eps 1e-10
16 #define ll long long
17 #define pa pair<int,int>
18 #define for0(i,n) for(int i=0;i<=(n);i++)
19 #define for1(i,n) for(int i=1;i<=(n);i++)
20 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
21 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
22 #define mod 20100403
23 using namespace std;
24 inline int read()
25 {
26     int x=0,f=1;char ch=getchar();
27     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
28     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
29     return x*f;
30 }
31 ll n,m,ans,inv[maxn];
32 void getinv()
33 {
34     inv[0]=inv[1]=1;
35     for2(i,2,maxn)
36      inv[i]=((mod/i+1)*inv[i-mod%i])%mod;
37 }
38 int main()
39 {
40     freopen("input.txt","r",stdin);
41     freopen("output.txt","w",stdout);
42     n=read();m=read();
43     getinv();
44     ans=n-m+1;
45     for2(i,n+2,n+m)ans*=i,ans%=mod;
46     for1(i,m)ans*=inv[i],ans%=mod;
47     printf("%lld\n",ans);
48     return 0;
49 }