[SCOI2008]\u7740\u8272\u65b9\u6848<\/p>\n
Time Limit:10000MS Memory Limit:165536K
Total Submit:20 Accepted:16
Case Time Limit:1000MS<\/p>\n
Description <\/strong><\/p>\n \u6709n\u4e2a\u6728\u5757\u6392\u6210\u4e00\u884c\uff0c\u4ece\u5de6\u5230\u53f3\u4f9d\u6b21\u7f16\u53f7\u4e3a1~n\u3002\u4f60\u6709k\u79cd\u989c\u8272\u7684\u6cb9\u6f06\uff0c\u5176\u4e2d\u7b2ci\u79cd\u989c\u8272\u7684\u6cb9\u6f06\u8db3\u591f\u6d82ci\u4e2a\u6728\u5757\u3002\u6240\u6709\u6cb9\u6f06\u521a\u597d\u8db3\u591f\u6d82\u6ee1\u6240\u6709\u6728\u5757\uff0c\u5373 c1+c2+…+ck=n\u3002\u76f8\u90bb\u4e24\u4e2a\u6728\u5757\u6d82\u76f8\u540c\u8272\u663e\u5f97\u5f88\u96be\u770b\uff0c\u6240\u4ee5\u4f60\u5e0c\u671b\u7edf\u8ba1\u4efb\u610f\u4e24\u4e2a\u76f8\u90bb\u6728\u5757\u989c\u8272\u4e0d\u540c\u7684\u7740\u8272\u65b9\u6848\u3002 <\/p>\n Input <\/strong><\/p>\n \u7b2c\u4e00\u884c\u4e3a\u4e00\u4e2a\u6b63\u6574\u6570k\uff0c\u7b2c\u4e8c\u884c\u5305\u542bk\u4e2a\u6574\u6570c1, c2, … , ck\u3002 <\/p>\n Output <\/strong><\/p>\n \u8f93\u51fa\u4e00\u4e2a\u6574\u6570\uff0c\u5373\u65b9\u6848\u603b\u6570\u6a211,000,000,007\u7684\u7ed3\u679c\u3002 <\/p>\n Sample Input <\/strong><\/p>\n 3 Sample Output <\/strong><\/p>\n 10<\/p>\n Hint <\/strong><\/p>\n \u3010\u6837\u4f8b2\u3011 Source [SCOI2008]\u7740\u8272\u65b9\u6848 Time Limit:10000MS Memory Limit:165536KTotal Submit:20 Accepted:16 Case Time Limit:1000MS Description \u6709n\u4e2a\u6728\u5757\u6392\u6210\u4e00\u884c\uff0c\u4ece\u5de6\u5230\u53f3\u4f9d\u6b21\u7f16\u53f7\u4e3a1~n\u3002\u4f60\u6709k\u79cd\u989c\u8272\u7684\u6cb9\u6f06\uff0c\u5176\u4e2d\u7b2ci\u79cd\u989c\u8272\u7684\u6cb9\u6f06\u8db3\u591f\u6d82ci\u4e2a\u6728\u5757\u3002\u6240\u6709\u6cb9\u6f06\u521a\u597d\u8db3\u591f\u6d82\u6ee1\u6240\u6709\u6728\u5757\uff0c\u5373 c1+c2+…+ck=n\u3002\u76f8\u90bb\u4e24\u4e2a\u6728\u5757\u6d82\u76f8\u540c\u8272\u663e\u5f97\u5f88\u96be\u770b\uff0c\u6240\u4ee5\u4f60\u5e0c\u671b\u7edf\u8ba1\u4efb\u610f\u4e24\u4e2a\u76f8\u90bb\u6728\u5757\u989c\u8272\u4e0d\u540c\u7684\u7740\u8272\u65b9\u6848\u3002 Input \u7b2c\u4e00\u884c\u4e3a\u4e00\u4e2a\u6b63\u6574\u6570k\uff0c\u7b2c\u4e8c\u884c\u5305\u542bk\u4e2a\u6574\u6570c1, c2, … , ck\u3002 Output \u8f93\u51fa\u4e00\u4e2a\u6574\u6570\uff0c\u5373\u65b9\u6848\u603b\u6570\u6a211,000,000,007\u7684\u7ed3\u679c\u3002 Sample Input 31 2 3 Sample Output 10 Hint \u3010\u6837\u4f8b2\u3011 Input 5 2 2 2 2 2 Output 39480 \u3010\u6837\u4f8b3\u3011 Input 10 1 1 2 2 3 3 4 4 5 5 Output 85937576 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/205"}],"collection":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=205"}],"version-history":[{"count":0,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/205\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=205"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=205"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
1 2 3<\/p>\n
Input
5
2 2 2 2 2
Output
39480
\u3010\u6837\u4f8b3\u3011
Input
10
1 1 2 2 3 3 4 4 5 5
Output
85937576
\u6570\u636e\u89c4\u6a21\u3011
50%\u7684\u6570\u636e\u6ee1\u8db3\uff1a1 <= k <= 5, 1 <= ci <= 3
100%\u7684\u6570\u636e\u6ee1\u8db3\uff1a1 <= k <= 15, 1 <= ci <= 5 <\/p>\n
<\/strong>\u8fd9\u9898\u4e00\u770b\u5c31\u77e5\u9053\u662f\u8981Dp\u7684\uff0c\u800c\u4e14\u72b6\u6001\u5f88\u9ebb\u70e6\uff0c\u597d\u5728c\u6700\u5927\u53ea\u67095\uff0c\u6240\u4ee5\u53ef\u4ee5\u7528\u4e00\u4e2a6\u7ef4\u6570\u7ec4\u8868\u793a
\uff0c\u5c31\u662f\u7b2ci\u4e2a\u8868\u793a\u5f53\u524d\u8fd8\u6709i\u4e2a\u7684\u989c\u8272\u8fd8\u6709\u51e0\u4e2a\uff0c\u8fd8\u8981\u4e00\u4e2aLast\u8868\u793a\u6700\u540e\u4e00\u4e2a\u662f\u54ea\u4e2a\u989c\u8272\u3002\u7136\u540e\u7528
Hash\u8868\u5b58\u50a8\u72b6\u6001\u5c31\u53ef\u4ee5\u4e86\u3002\u3002unsigned long long\u4e2d\u7684-1\u5c31\u662f\u6700\u5927\u503c\u3002\u3002
Code\uff1a
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<cstring>
#define rep(i,n) for(int i=0;i<n;i++)
#define pb push_back
using namespace std;
const int inf=~0U>>1,c=6,seed=17,mod=1000000007,size=17771;
typedef unsigned long long ull;
int n;
struct State
{
int Num,Last;
State(){memset(Num,0,sizeof(Num));}
ull HashCode() const
{
ull ret=0;
rep(i,c) ret*=seed,ret+=Num[i];
ret*=seed;return ret+=Last;
}
State Next()
{
State s=*this;
s.Num[Last]–;s.Num[Last-1]++;return s;
}
bool Legal(){return Num[Last]>0&&Last>0;}
void operator=(const State&o)
{
memcpy(Num,o.Num,sizeof(Num));
Last=o.Last;
}
};
struct Hash
{
struct Node
{
ull key,Count;
Node*next;
Node(ull _key,Node*_next):key(_key),next(_next),Count(-1){}
}*H[size];
Hash(){memset(H,0,sizeof(H));}
ull& Find(const State&a)
{
ull code=a.HashCode(),h=code%size;
for(Node*i=H[h];i;i=i->next)if(i->key==code) return i->Count;
return H[h]=new Node(code,H[h]),H[h]->Count;
}
}H;
ull dfs(State S,int Left)
{
ull&x=H.Find(S);if(x!=-1) return x;
if(!S.Legal()) return x=0;
if(Left==1) return x=1;
x=0;
State NewS=S.Next();
for(int i=1;i<c;i++)
{
NewS.Last=i;
if(i!=S.Last&&S.Num[i])
{
x+=S.Num[i]*dfs(NewS,Left-1);
x%=mod;
}
if(i==S.Last&&S.Num[i]>1)
{
x+=(S.Num[i]-1)*dfs(NewS,Left-1);
x%=mod;
}
}
return x;
}
int main()
{
\/\/freopen("in","r",stdin);
State now;ull ans=0;
int n,x,s=0;cin>>n;rep(i,n) cin>>x,now.Num[x]++,s+=x;
rep(i,c) now.Last=i,ans+=now.Num[i]*dfs(now,s),ans%=mod;
cout<<ans<<endl;
}<\/p>\n","protected":false},"excerpt":{"rendered":"