Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này

Code mẫu của flashmt

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <vector>
#define quit(a,b) cout << a << " " << b << endl, exit(0);
using namespace std;

int n,m,f[200200];
vector <int> a,b,c[200200];

int mod(int a,int b)
{
    if (a>=0) return a%b;
    if ((-a)%b) return b-(-a)%b;
    return 0;
}

void check(int d)
{
    for (int i=0,j=0;i<=m;i++)
    {
        f[i]=1;
        while (j<=m && a[j]+d<a[i]) j++;
        if (j<=m && a[j]+d==a[i]) f[i]=f[j]+1;
        if (f[i]==n) quit(a[i]-(n-1)*d,d);
    }
}

int main()
{
    int cnt=1,x;
    cin >> n;
    for (int i=0;i<n*2;i++) scanf("%d",&x), a.push_back(x); 
    sort(a.begin(),a.end());
    for (int i=1;i<n*2;i++)
        if (a[i]==a[i-1]) 
        {
            if (++cnt==n) quit(a[i],0);
        }
        else a[++m]=a[i], cnt=1;
    for (int l=1;l<=2;l++)
        for (int i=0;i+l<=m;i++)
            b.push_back(a[i+l]-a[i]);
    sort(b.begin(),b.end());
    cnt=1;
    for (int i=1;i<int(b.size());i++)
        if (b[i]==b[i-1]) cnt++;
        else c[cnt].push_back(b[i-1]), cnt=1;
    for (int i=m+1;i;i--)
        for (int j=0;j<int(c[i].size());j++)
            check(c[i][j]);
}

Code mẫu của ladpro98

#include <bits/stdc++.h>

using namespace std;

const int N = 200005;

int n, m;
int a[N];

int goLeft(int from, int diff) {
    int ans = 0;
    for (int i = from, j; i > 0; i = j) {
        ++ans;
        j = i - 1;
        while (j >= 1 && a[i] - diff < a[j]) --j;
        if (j > 0 && a[i] - diff == a[j]) continue;
        return ans;
    }
    return ans;
}

int goRight(int from, int diff) {
    int ans = 0;
    for (int i = from, j; i <= m; i = j) {
        ++ans;
        j = i + 1;
        while (j <= m && a[j] < a[i] + diff) ++j;
        if (j <= m && a[i] + diff == a[j]) continue;
        return ans;
    }
    return ans;
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
#ifndef ONLINE_JUDGE
    freopen("LSCSC.in", "r", stdin);
#endif
    cin >> n;
    m = n + n;
    for (int i = 1; i <= m; ++i) cin >> a[i];
    sort(a + 1, a + 1 + m);
    if (n == 1) {
        cout << a[1] << ' ' << 0 << endl;
        return 0;
    }
    while (1) {
        int u = rand() % (m - 1) + 2;
        int v = u - 1;
        if (rand() & 1) {
            u = rand() % (m - 2) + 3;
            v = u - 2;
        }
        int diff = a[u] - a[v];
        int L = goLeft(v, diff);
        int R = goRight(u, diff);
        if (L + R >= n) {
            cout << a[u] - diff * min(L, n) << ' ' << diff << endl;
            break;
        }
    }
    return 0;
}

Code mẫu của RR

#include <sstream>
#include <iomanip>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <deque>
#include <complex>

#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
#define FORN(i,a,b) for(int i=(a),_b=(b);i<_b;i++)
#define DOWN(i,a,b) for(int i=a,_b=(b);i>=_b;i--)
#define SET(a,v) memset(a,v,sizeof(a))
#define sqr(x) ((x)*(x))
#define ll long long
#define F first
#define S second
#define PB push_back
#define MP make_pair

#define DEBUG(x) cout << #x << " = "; cout << x << endl;
#define PR(a,n) cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl;
#define PR0(a,n) cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl;
using namespace std;

//Buffer reading
int INP,AM,REACHEOF;
#define BUFSIZE (1<<12)
char BUF[BUFSIZE+1], *inp=BUF;
#define GETCHAR(INP) { \
    if(!*inp) { \
        if (REACHEOF) return 0;\
        memset(BUF,0,sizeof BUF);\
        int inpzzz = fread(BUF,1,BUFSIZE,stdin);\
        if (inpzzz != BUFSIZE) REACHEOF = true;\
        inp=BUF; \
    } \
    INP=*inp++; \
}
#define DIG(a) (((a)>='0')&&((a)<='9'))
#define GN(j) { \
    AM=0;\
    GETCHAR(INP); while(!DIG(INP) && INP!='-') GETCHAR(INP);\
    if (INP=='-') {AM=1;GETCHAR(INP);} \
    j=INP-'0'; GETCHAR(INP); \
    while(DIG(INP)){j=10*j+(INP-'0');GETCHAR(INP);} \
    if (AM) j=-j;\
}
//End of buffer reading

const long double PI = acos((long double) -1.0);

int n, a[200111], f[200111];
map<int,int> cnt;
pair<int,int> x[200111];

bool check() {
    int j = 1;
    FOR(i,1,n) {
        while (j < n && a[i] == a[j+1]) ++j;
        if (j - i + 1 >= n/2) {
            cout << a[i] << ' ' << 0 << endl;
            return true;
        }
    }
    return false;
}

int main() {
    scanf("%d", &n); n *= 2;
    FOR(i,1,n) scanf("%d", &a[i]);
    sort(a+1, a+n+1);

    if (check()) return 0;

    n = unique(a+1, a+n+1) - a - 1;

    FOR(i,2,n) {
        cnt[a[i] - a[i-1]]++;
        if (i > 2) cnt[a[i] - a[i-2]]++;
    }
    int now = 0;
    for(map<int,int> :: iterator it = cnt.begin(); it != cnt.end(); ++it)
        if (it->S >= n/4)
            x[++now] = MP(it->S, it->F);

    sort(x+1, x+now+1);

    FORD(t,now,1) {
        int best = 0, save = -1;
        int j = n;
        FORD(i,n,1) {
            while (j > i && a[j-1] >= a[i] + x[t].S) --j;
            if (a[j] == a[i] + x[t].S) {
                f[i] = f[j] + 1;
            }
            else f[i] = 1;

            if (f[i] > best) {
                best = f[i];
                save = i;
            }
        }
        if (best >= n/2) {
            printf("%d %d\n", a[save], x[t].S);
            return 0;
        }
    }
    return 0;
}

Code mẫu của hieult

#include<cstdio>
#include<cmath>
#include<math.h>
#include<cstring>
#include<cstdlib>
#include<cassert>
#include<ctime>
#include<algorithm>
#include<iterator>
#include<iostream>
#include<cctype>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<list>
#define fi first
#define se second
#define PB push_back
#define MP make_pair
#define ep 0.00000001
#define oo 1111111111
#define mod 1000000007
#define TR(c, it) for(typeof((c).begin()) it=(c).begin(); it!=(c).end(); it++)
#define rep(i, n) for(int i = 0; i < n; i++)
#define FOR(i, a, b) for(int i = a; i <= b; i++)
#define FORD(i, a, b) for(int i = a; i >= b; i--)
//#include <conio.h>
//#define g 9.81
#define maxn 100005
double const PI=4*atan(1.0);

const int bfsz = 1 << 16; char bf[bfsz + 5]; int rsz = 0;int ptr = 0;
char gc() { if (rsz <= 0) { ptr = 0; rsz = fread(bf, 1, bfsz, stdin); if (rsz <= 0) return EOF; } --rsz; return bf[ptr++]; }
void ga(char &c) { c = EOF; while (!isalpha(c)) c = gc(); }
int gs(char s[]) { int l = 0; char c = gc(); while (isspace(c)) c = gc(); while (c != EOF && !isspace(c)) { s[l++] = c; c = gc(); } s[l] = '\0'; return l; }
template<class T> bool gi(T &v) {
    v = 0; char c = gc(); while (c != EOF && c != '-' && !isdigit(c)) c = gc(); if (c == EOF) return false; bool neg = c == '-'; if (neg) c = gc();
    while (isdigit(c)) { v = v * 10 + c - '0'; c = gc(); } if (neg) v = -v; return true;
}

using namespace std;

typedef pair<int, int> II;
typedef vector<int> VI;
typedef vector<II> VII;
typedef vector<VI> VVI;
typedef vector<VII> VVII;

void OPEN(){
    freopen("A.in","r",stdin);
    freopen("A.out","w",stdout);
}

int n;
int a[maxn + maxn];
map<long long, int> M1;

int main(){


   // OPEN();

    clock_t start = clock();
    gi(n);
    rep(i, n + n) gi(a[i]);
    sort(a, a + n + n);

    if(n == 1){
        printf("%d %d", a[0], 0);
        return 0;
    }

    if(n == 2){
        printf("%d %d", a[0], a[1] - a[0]);
        return 0;
    }


    rep(i, n + n){
        if(i + 1 < n + n) M1[a[i + 1] - a[i]]++;
        if(i + 2 < n + n) M1[a[i + 2] - a[i]]++;
    } 

    map<long long, int>::iterator it;
    it = M1.begin();

  //  printf("%d\n",(clock() - start));
    do{  
        if((*it).se >= n / 2){
            int x = (*it).fi;

            bool flag = false;
            if(x == 0){
                int run = 1;
                FOR(i, 1, n + n - 1){
                    if(a[i] == a[i - 1])
                        run++;
                    else run = 1;
                    if(run == n){
                        printf("%d 0\n", a[i]);
                        flag = true;
                        break;
                    }
                }
            }

            else{

                int f[maxn + maxn] = {0};
                int run = 0;
                f[0] = 1;
                FOR(i, 1, n + n - 1){
                    while(run < i - 1 && (a[run] < a[i] - x)) run++;
                    if(run >= 0 && a[run] + x == a[i]) f[i] = f[run] + 1;
                    else f[i] = 1;
                    if(f[i] == n){
                        printf("%d %d\n", a[i] - (n - 1) * x, x);
                        flag = true;
                        break;
                    }
                }

            }
            if(flag) break;
        }

    }while(M1.value_comp()(*it++, *M1.rbegin()));


  //  printf("%d",(clock() - start));
}