题解：P10467 [CCC 2007] Snowflake Snow Snowflakes

Yuneko · 2024-05-16 15:22:22 · 题解

题目链接

P10467 [CCC 2007] Snowflake Snow Snowflakes

解题思路

字符串哈希板子题。

思路就是我们给每个数列的所有排列都哈希一个值，然后判断是否有不同的数列的哈希值相同，如果有，就输出 Twin snowflakes found.，否则就输出 No two snowflakes are alike.。

参考代码

这里使用双哈希。

#include<bits/stdc++.h>
using namespace std;
#define map unordered_map
#define forl(i,a,b) for(register long long i=a;i<=b;i++)
#define forr(i,a,b) for(register long long i=a;i>=b;i--)
#define forll(i,a,b,c) for(register long long i=a;i<=b;i+=c)
#define forrr(i,a,b,c) for(register long long i=a;i>=b;i-=c)
#define lc(x) x<<1
#define rc(x) x<<1|1
//#define mid ((l+r)>>1)
#define cin(x) scanf("%lld",&x)
#define cout(x) printf("%lld",x)
#define lowbit(x) (x&-x)
#define pb push_back
#define pf push_front
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define endl '\n'
#define QwQ return 0;
#define ll long long
#define ull unsigned long long
#define lcm(x,y) x/__gcd(x,y)*y
#define Sum(x,y) 1ll*(x+y)*(y-x+1)/2
#define aty cout<<"Yes\n";
#define atn cout<<"No\n";
#define cfy cout<<"YES\n";
#define cfn cout<<"NO\n";
#define xxy cout<<"yes\n";
#define xxn cout<<"no\n";
#define printcf(x) x?cout<<"YES\n":cout<<"NO\n";
#define printat(x) x?cout<<"Yes\n":cout<<"No\n";
#define printxx(x) x?cout<<"yes\n":cout<<"no\n";
ll t;
ll Base1=666,Base2=223,Base3=771;
ll mod1=1e9+7,mod2=998244353,mod3=1e9+9;
map<ll,map<ll,ll>>mp;
ll n,a[10];
ll nxt(ll x){
    if(x==6)
        return 1;
    return x+1;
}
ll lst(ll x){
    if(x==1)
        return 6;
    return x-1;
}
void dfs1(ll st){
    ll L=st,sum1=0,sum2=0,sum3=0;
    forl(i,1,6){
        sum1*=Base1,sum2*=Base2,sum3*=Base3;
        sum1+=a[L],sum2+=a[L],sum3+=a[L];
        L=nxt(L);
    }
    if(mp[sum1][sum2])
    {
        cout<<"Twin snowflakes found.\n";
        exit(0);
    }
    mp[sum1][sum2]=1;
}
void dfs2(ll st){
    ll L=st,sum1=0,sum2=0,sum3=0;
    forl(i,1,6){
        sum1*=Base1,sum2*=Base2,sum3*=Base3;
        sum1+=a[L],sum2+=a[L],sum3+=a[L];
        L=lst(L);
    }
    if(mp[sum1][sum2])
    {
        cout<<"Twin snowflakes found.\n";
        exit(0);
    }
    mp[sum1][sum2]=1;
}
void solve()
{
    cin>>n;
    forl(i,1,n)
    {
        forl(j,1,6)
            cin>>a[j];
        forl(j,1,6)
            dfs1(j),dfs2(j);
    }
    cout<<"No two snowflakes are alike.\n";
}
int main()
{
    IOS;
    t=1;
//  cin>>t;
    while(t--)
        solve();
    QwQ;
}