1145 Hashing - Average Search Time (25 分)

#include<bits/stdc++.h>
using namespace std;
#define debug puts("YES");
#define rep(x,y,z) for(int (x)=(y);(x)<(z);(x)++)
#define ll long long
#define ull unsigned long long

#define lrt int l,int r,int rt
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define root l,r,rt
#define mst(a,b) memset((a),(b),sizeof(a))
#define pii pair<int,int>
#define piii pair<int,pii>
#define fi first                                  
#define se second
#define mk(x,y) make_pair(x,y)

#define base 2333
const int mod=1e9+7;
const int maxn=1e5+100;
const int ub=1e6;
ll powmod(ll x,ll y){ll t; for(t=1;y;y>>=1,x=x*x%mod) if(y&1) t=t*x%mod; return t;}
ll gcd(ll x,ll y){
    if(y==0) return x;
    return gcd(y,x%y);
}
int maxv,n,m;
int judge(int x){
    if(x==2) return 1;
    if(x==1||x==0) return 0;
    for(int i=2;i*i<=x;i++){
        if(x%i==0) return 0;
    }
    return 1;
}
int gao(int x,int y){
    return x*x%y;
}
int table[maxn];
int main(){
    mst(table,-1);
    scanf("%d%d%d",&maxv,&n,&m);
    while(judge(maxv)==0) maxv++;
    rep(i,0,n){
        int x;scanf("%d",&x);
        int pos=x%maxv,flag=0;
        rep(j,0,maxv){
            int tp=(pos+j*j)%maxv;
            if(table[tp]==-1){
                table[tp]=x;
                flag=1;
                break;
            }
        }
        if(flag==0) printf("%d cannot be inserted.\n",x);
    }
    int tot=0;
    rep(i,0,m){
        int x,j=0,p=0;scanf("%d",&x);
        p=x%maxv;
        for(;j<maxv;j++){
            tot++;
            int tp=(p+j*j)%maxv;
            if(table[tp]==-1){
                break;
            }else if(table[tp]==x){
                break;
            }
        }
        if(j==maxv) tot++;
    }
    printf("%.1f\n",1.0*tot/m);
    return 0;
}