Divide by Zero 2017 and Codeforces Round #399 (Div. 1 + Div. 2, combined) C. Jon Snow and his Favou-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_45714303/article/details/125162975

本文探讨了如何在C++中通过map数据结构处理一组整数，通过哈希函数gethash()和自定义比较函数，解决数据排序和查找问题。重点介绍了如何处理k次异或操作对数组的影响，以及如何利用哈希表优化查询效率。

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#include <iostream>  
#include <stdio.h>  
#include <string.h>   
#include <stack>  
#include <queue>   
#include <map>  
#include <set>  
#include <vector>  
#include <math.h>  
#include <bitset>  
#include <algorithm>  

using namespace std;

#define X first
#define Y second
#define eps  1e-2
#define gcd __gcd
#define pb push_back
#define PI acos(-1.0)
#define lowbit(x) (x)&(-x)
#define bug printf("!!!!!\n");
#define mem(x,y) memset(x,y,sizeof(x))

typedef long long LL;
typedef long double LD;
typedef pair<int,int> pii;
typedef unsigned long long uLL;

const int N = 1e5+2;
const int INF  = 1<<30;
const int mod  = 1e9+7;

int n,k,x,a[N];

map<uLL,int> mp;

uLL gethash(){
    uLL now=0,p=13;
    for(int i=1;i<=n;i++) now=now*p+(uLL)a[i];
    return now;
}

pair<int,int> res[N];

void solve(){
    scanf("%d%d%d",&n,&k,&x);
    int maxi=0,mini=1e9,cnt=0,K=k;
    for(int i=1;i<=n;i++) {
        scanf("%d",&a[i]);
        maxi=max(maxi,a[i]);
        mini=min(mini,a[i]);
    }
    res[cnt]={maxi,mini};
    while(k--){
        sort(a+1,a+1+n);
        int maxi=0,mini=1e9;
        for(int i=1;i<=n;i++){
            if(i%2==1) a[i]^=x;
            maxi=max(maxi,a[i]);
            mini=min(mini,a[i]);
            // cout<<a[i]<<" ";
        }
        // cout<<endl;
        uLL now=gethash();
        ++cnt;
        if(mp.count(now)==1){
            int pre=mp[now],len=cnt-pre;
            int nd=(K-pre)%len+pre;
            // cout<<cnt<<endl;
            // cout<<pre<<" "<<len<<" "<<nd<<endl;
            // cout<<nd<<endl;
            cout<<res[nd].first<<" "<<res[nd].second<<endl;
            return;
        }
        res[cnt]={maxi,mini};
        mp[now]=cnt;
    }
    cout<<res[cnt].first<<" "<<res[cnt].second<<endl;
    
    
    return;
}

int main()
{
//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
//    ios::sync_with_stdio(false);
    int t = 1;
    //scanf("%d",&t);
    while(t--){
    //    printf("Case %d: ",cas++);
        solve();
    }
    return 0;
}