HDU 4869 Turn the pokers(思维+逆元)
Posted freeloop
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了HDU 4869 Turn the pokers(思维+逆元)相关的知识,希望对你有一定的参考价值。
考试的时候没有做出来。。。
想到了答案一定是一段连续的区间,一直在纠结BFS判断最后的可行1数。
原来直接模拟一遍就可以算出来最后的端点。。。
剩下的就是组合数取模了,用逆元就行了。。。
# include <cstdio> # include <cstring> # include <cstdlib> # include <iostream> # include <vector> # include <queue> # include <stack> # include <map> # include <set> # include <cmath> # include <algorithm> using namespace std; # define lowbit(x) ((x)&(-x)) # define pi 3.1415926535 # define eps 1e-9 # define MOD 1000000009 # define INF 1000000000 # define mem(a,b) memset(a,b,sizeof(a)) # define FOR(i,a,n) for(int i=a; i<=n; ++i) # define FO(i,a,n) for(int i=a; i<n; ++i) # define bug puts("H"); # define lch p<<1,l,mid # define rch p<<1|1,mid+1,r # define mp make_pair # define pb push_back typedef pair<int,int> PII; typedef vector<int> VI; # pragma comment(linker, "/STACK:1024000000,1024000000") typedef long long LL; int Scan() { int res=0, flag=0; char ch; if((ch=getchar())==‘-‘) flag=1; else if(ch>=‘0‘&&ch<=‘9‘) res=ch-‘0‘; while((ch=getchar())>=‘0‘&&ch<=‘9‘) res=res*10+(ch-‘0‘); return flag?-res:res; } void Out(int a) { if(a<0) {putchar(‘-‘); a=-a;} if(a>=10) Out(a/10); putchar(a%10+‘0‘); } const int N=100005; //Code begin... LL f[N]; LL pow_mod(LL a, LL n, LL mod){ LL ret=1, tmp=a%mod; while (n) { if (n&1) ret=ret*tmp%MOD; tmp=tmp*tmp%MOD; n>>=1; } return ret; } LL inv(LL a, LL mod){return pow_mod(a,mod-2,mod);} void init(){ f[0]=1; FO(i,1,N) f[i]=(f[i-1]*i)%MOD; } int main () { int n, m, x, l, r, tmpl, tmpr; LL ans; init(); while (~scanf("%d%d",&n,&m)) { l=r=0; ans=0; FOR(i,1,n) { scanf("%d",&x); if (l>=x) tmpl=l-x; else if(r>=x) tmpl=((l%2)==(x%2))?0:1; else tmpl=x-r; if (r+x<=m) tmpr=r+x; else if(l+x<=m) tmpr=(((l+x)%2)==(m%2)?m:m-1); else tmpr=2*m-l-x; l=tmpl; r=tmpr; } for (int i=l; i<=r; i+=2) ans=(ans+(f[m]*inv(f[i]*f[m-i]%MOD,MOD))%MOD)%MOD; printf("%lld\n",ans); } return 0; }
以上是关于HDU 4869 Turn the pokers(思维+逆元)的主要内容,如果未能解决你的问题,请参考以下文章
HDU4869:Turn the pokers(费马小定理+高速幂)
HDU 4869 Turn the pokers(思维+逆元)
HDU 4869 Turn The Pokers 思维+组合