OJ-Problems-Source/HDOJ/4869_autoAC.cpp

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#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;
#define mod 1000000009
#define LL __int64
#define maxn 100000+5
LL f[maxn];
void set()
{
int i;
f[0] = 1;
for(i = 1; i<maxn; i++)
f[i] = (f[i-1]*i)%mod;
}
LL quickmod(LL a,LL b)
{
LL ans = 1;
while(b)
{
if(b&1)
{
ans = (ans*a)%mod;
b--;
}
b/=2;
a = ((a%mod)*(a%mod))%mod;
}
return ans;
}
int main()
{
int n,m,i,j,k,l,r,x,ll,rr;
set();
while(~scanf("%d%d",&n,&m))
{
l = r = 0;
for(i = 0; i<n; i++)
{
scanf("%d",&x);
if(l>=x) ll = l-x;
else if(r>=x) ll = ((l%2)==(x%2))?0:1;
else ll = x-r;
if(r+x<=m) rr = r+x;
else if(l+x<=m) rr = (((l+x)%2) == (m%2)?m:m-1);
else rr = 2*m-(l+x);
l = ll,r = rr;
}
LL sum = 0;
for(i = l; i<=r; i+=2)
sum+=((f[m]%mod)*(quickmod((f[i]*f[m-i])%mod,mod-2)%mod))%mod;
printf("%I64d\n",sum%mod);
}
return 0;
}