Warsaw University Contest Petrozavodsk, Thursday, January 31, 2008 F题，Gym100096F

题目分析：

集合双Hash

#include<bits/stdc++.h>
#define Mod1 1000000009
#define Mod2 1000000007
#define maxn 510
#define LL long long 
#define mp make_pair
#define Pii pair<LL,LL>
#define fi first
#define se second
#define push_back
using namespace std;
LL hash1[maxn],hash2[maxn];
int n,seg[maxn];
LL ksm(LL base,LL m,LL mod){
    LL res=1;
    while(m){
        if(m&1) res=(res*base)%mod;
        base=(base*base)%mod;
        m>>=1;
    }
    return res;
}
void pre_hash(){
    int ans1=0,ans2=0;
    for(int i=0;i<=500;i++){
        hash1[i]=ksm(i,i+5,Mod1);
        hash2[i]=ksm(i,i+5,Mod2);
    }
}
Pii getHash(set<int> &str){
    set<int>::iterator it;
    LL ans1=0,ans2=0;
    for(it=str.begin();it!=str.end();++it){
        ans1=(ans1+hash1[*it])%Mod1;
        ans2=(ans2+hash2[*it])%Mod2;
    }
    return mp(ans1,ans2);
}
set<int> s;
set<Pii> ss;
int main(){
    freopen("numbereater.in","r",stdin);
    freopen("numbereater.out","w",stdout);
    pre_hash();
    cin>>n;
    for(int i=1;i<=n;i++) scanf("%d",&seg[i]);
    for(int i=1;i<=n;i++){
        s.clear();
        for(int j=i;j<=n;j++){
            s.insert(seg[j]);
            ss.insert(getHash(s));
        }
    }
    cout<<ss.size();
    return 0;
}