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 <map>
using namespace std;

int main()
{
    int n, x[1010], y[1010], ans = 0;

    cin >> n;
    for (int i = 0; i < n; i++) cin >> x[i] >> y[i];

    for (int i = 0; i < n; i++)
    {
        map <long long,int> d;
        for (int j = 0; j < n; j++)
            ans += d[1LL* (x[i] - x[j]) * (x[i] - x[j]) + 1LL * (y[i] - y[j]) * (y[i] - y[j])]++;
    }

    cout << ans << endl;
}

Code mẫu của happyboy99x

#include<cstdio>
#include<algorithm>
using namespace std;

const int N = 1000 + 2;
pair<long long, int> d[N][N];
long long sd[N][N]; 
int x[N], y[N], n;

long long sqr(long long x) {
    return x * x;
}

long long dis(int u, int v) {
    return sqr(x[u] - x[v]) + sqr(y[u] - y[v]);
}

int main() {
    scanf("%d", &n);
    for(int i = 0; i < n; ++i) scanf("%d%d",x+i,y+i);
    for(int i = 0; i < n; ++i) {
        for(int j = 0; j < n; ++j) d[i][j] = make_pair(dis(i, j), j), sd[i][j] = d[i][j].first;
        sort(d[i], d[i]+n);
    }
    int res = 0;
    for(int i = 0; i < n; ++i)
        for(int b = 0, e = 1; e <= n; ++e) if(d[i][e].first != d[i][b].first) {
            for(int u = b; u < e; ++u) for(int v = u+1; v < e; ++v)
                res += sd[d[i][u].second][d[i][v].second] != d[i][u].first;
            b = e;
        }
    printf("%d\n", res);
    return 0;
}

Code mẫu của ladpro98

program spoj_triland;
uses    math;
const   fi='';
var     x,y:array[1..1111] of int64;
        f:array[1..1111] of int64;
        n,i,j,c,t:longint;
        inp:text;
        res:int64;
procedure swap(i,j:longint);
var     t:int64;
begin
        t:=f[i];
        f[i]:=f[j];
        f[j]:=t;
end;

procedure sort(l,r:longint);
var     pivot:int64;
        i,j:longint;
begin
        if l>=r then exit;
        pivot:=f[random(r-l+1)+l];
        i:=l;j:=r;
        repeat
                while f[i]<pivot do inc(i);
                while f[j]>pivot do dec(j);
                if i<=j then
                begin
                        if i<j then swap(i,j);
                        inc(i);
                        dec(j);
                end;
        until i>j;
        sort(l,j);
        sort(i,r);
end;

procedure input;
var     i:longint;
begin
        assign(inp,fi);
        reset(inp);
        readln(inp,n);
        for i:=1 to n do
        begin
                readln(inp,x[i],y[i]);
        end;
        close(inp);
end;

begin
        res:=0;
        input;
        for i:=1 to n do
        begin
                t:=1;

                for j:=1 to i-1 do
                begin
                        f[t]:=sqr(x[i]-x[j])+sqr(y[i]-y[j]);
                        inc(t);
                end;
                for j:=i+1 to n do
                begin
                        f[t]:=sqr(x[i]-x[j])+sqr(y[i]-y[j]);
                        inc(t);
                end;
                t:=n-1;
                sort(1,t);
                j:=1;
                while j<=t do
                begin
                        c:=1;

                        while (f[j]=f[j+1]) do
                        begin
                                inc(c);
                                inc(j);
                        end;
                        inc(res,(c*(c-1)) div 2);
                        inc(j);
                end;

        end;
        write(res);
end.

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);

struct Point {
    ll x, y;
    Point(ll x = 0, ll y = 0) : x(x), y(y) {}

    Point operator + (Point a) { return Point(x+a.x, y+a.y); }
    Point operator - (Point a) { return Point(x-a.x, y-a.y); }

    void read() {
        int _x, _y; scanf("%d%d", &_x, &_y);
        x = _x; y = _y;
    }

    ll sqlen() { return x*x + y*y; }
} a[1011];

ll x[1011];

int main() {
    int n; scanf("%d", &n);
    FOR(i,1,n) a[i].read();

    long long res = 0;

    FOR(i,1,n) {
        FOR(j,1,n) x[j] = (a[i] - a[j]).sqlen();

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

        int j = 2;
        FOR(i,2,n) {
            while (j < n && x[j+1] == x[i]) ++j;
            res += j - i;
        }
    }
    cout << res << endl;
    return 0;
}

Code mẫu của hieult

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

#include <ctime>
#include <deque>
#include <bitset>
#include <cctype>
#include <utility>
#include <cassert>

using namespace std;

typedef long long ll;
typedef double ld;
typedef unsigned int ui;
typedef unsigned long long ull;

#define Rep(i,n) for(int i = 0; i < (n); ++i)
#define Repd(i,n) for(int i = (n)-1; i >= 0; --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)
#define Fit(i,v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
//#define Fitd(i,v) for(__typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))

template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; }
template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template<class T> T sqr(T x) { return x * x; }
template<class T> T cube(T x) { return x * x * x; }
template<class T> int getbit(T s, int i) { return (s >> i) & 1; }
template<class T> T onbit(T s, int i) { return s | (T(1) << i); }
template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); }
template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); }

const int bfsz = 1 << 16;
char bf[bfsz + 5];
int rsz = 0;
int ptr = 0;
char gc() {
    if (rsz <= 0) {
        ptr = 0;
        rsz = (int) 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;
}

typedef pair<int, int> II;

const ld PI = acos(-1.0);
const ld eps = 1e-9;

const int dr[] = {0, +1, 0, -1};
const int dc[] = {+1, 0, -1, 0};

const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const ll mod = (ll)1e9 + 7;

#define maxn 1005

int n;
ll x[maxn], y[maxn], f[maxn][maxn];



int  main()
{
//  freopen("in.txt", "r", stdin);

    scanf("%d", &n);
    For(i, 1, n) cin >> x[i] >> y[i];
    For(i, 1, n) For(j, 1, n) f[i][j] = sqr(x[i] - x[j]) + sqr(y[i] - y[j]);

    int res = 0;
    For(i, 1, n) {
        vector<ll> V;
        For(j, 1, n) V.pb(f[i][j]);
        V.pb(-1); V.pb(linf);
        sort(all(V));

        int run = 1;
        Rep(i, sz(V) - 1){
            if(V[i] == V[i + 1]) run++;
            else run = 1;
            res += run - 1;
        }
    }

    cout << res;

    return 0;
}

Code mẫu của skyvn97

#include<stdio.h>
#define MAX   2000
typedef unsigned long long ull;
struct point
{
       ull x;
       ull y;
};
struct distance
{
       ull dis;
       ull n;
};
point a[MAX];
ull dist[MAX][MAX];
distance dsort[MAX][MAX];
ull n,res;
void merge(distance a[],int left,int mid,int right)
{
     distance b[MAX];
     distance c[MAX];
     int i,j,k;
     for (i=left;i<=mid;i=i+1) b[i-left+1]=a[i];
     for (i=mid+1;i<=right;i=i+1) c[i-mid]=a[i];
     j=1;
     k=1;
     for (i=left;i<=right;i=i+1)
         {
          if (j>mid-left+1)
             {
              a[i]=c[k];
              k=k+1;
              continue;
             }
          if (k>right-mid)
             {
              a[i]=b[j];
              j=j+1;
              continue;
             }
          if (b[j].dis<c[k].dis)
             {
              a[i]=b[j];
              j=j+1;
              continue;
             }
          a[i]=c[k];
          k=k+1;
         }
}
void mergesort(distance a[],int left,int right)
{
     if (left>=right) return;
     int mid=(left+right)/2;
     mergesort(a,left,mid);
     mergesort(a,mid+1,right);
     merge(a,left,mid,right);
}
void init(void)
{
     ull i,j,k;
     scanf("%llu",&n);
     for (i=1;i<=n;i=i+1)
         {
          scanf("%llu",&a[i].x);          
          scanf("%llu",&a[i].y);
         }
     for (i=1;i<=n;i=i+1)
         for (j=1;j<=n;j=j+1)
             {
              dist[i][j]=(a[i].x-a[j].x)*(a[i].x-a[j].x)+(a[i].y-a[j].y)*(a[i].y-a[j].y);
              dsort[i][j].dis=dist[i][j];
              dsort[i][j].n=j;              
             }
     ull res=0;
     for (i=1;i<=n;i=i+1)
         {
          mergesort(dsort[i],1,n);
          for (j=1;j<n;j=j+1)
              for (k=j+1;k<=n;k=k+1)
                  {
                   if (dsort[i][j].dis<dsort[i][k].dis) break;
                   if (dist[dsort[i][j].n][dsort[i][k].n]!=dsort[i][j].dis) res++;
                  }
         }
     printf("%llu",res);
}
int main(void)
{
    init();
    return 0;
}