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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4.  
  5. using namespace std;
  6.  
  7. struct Point {
  8.     long long x, y;
  9.     bool operator<(const Point& other) const {
  10.         if (x != other.x) return x < other.x;
  11.         return y < other.y;
  12.     }
  13.     bool operator==(const Point& other) const {
  14.         return x == other.x && y == other.y;
  15.     }
  16. };
  17.  
  18. // Kvadrat rastojanja izmedu dve tacke
  19. long long distSq(Point p1, Point p2) {
  20.     return (p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y);
  21. }
  22.  
  23. int main() {
  24.     vector<Point> p(4);
  25.     for (int i = 0; i < 4; i++) {
  26.         if (!(cin >> p[i].x >> p[i].y)) return 0;
  27.     }
  28.  
  29.     // Sortiranjem dobijamo fiksni raspored temena
  30.     sort(p.begin(), p.end());
  31.  
  32.     // Provera da li su tacke razlicite (romb ne može biti tacka ili duž)
  33.     for (int i = 0; i < 3; i++) {
  34.         if (p[i] == p[i+1]) {
  35.             cout << "NE" << endl;
  36.             return 0;
  37.         }
  38.     }
  39.  
  40.     // Kod sortiranih tacaka, dijagonale su (p0, p3) i (p1, p2)
  41.     // 1. Uslov: Dijagonale se polove (središta su ista)
  42.     bool isParallelogram = (p[0].x + p[3].x == p[1].x + p[2].x) && 
  43.                            (p[0].y + p[3].y == p[1].y + p[2].y);
  44.  
  45.     // 2. Uslov: Sve stranice su jednake (romb)
  46.     // Stranice su p0-p1, p1-p3, p3-p2, p2-p0
  47.     bool allSidesEqual = (distSq(p[0], p[1]) == distSq(p[1], p[3])) &&
  48.                          (distSq(p[1], p[3]) == distSq(p[3], p[2])) &&
  49.                          (distSq(p[3], p[2]) == distSq(p[2], p[0]));
  50.  
  51.     // Dodatna provera: Površina ne sme biti nula (tacke nisu kolinearne)
  52.     // Vektorski proizvod (p1-p0) i (p2-p0)
  53.     long long area2 = abs((p[1].x - p[0].x) * (p[2].y - p[0].y) - 
  54.                           (p[1].y - p[0].y) * (p[2].x - p[0].x));
  55.  
  56.     if (isParallelogram && allSidesEqual && area2 > 0) {
  57.         cout << "DA" << endl;
  58.     } else {
  59.         cout << "NE" << endl;
  60.     }
  61.  
  62.     return 0;
  63. }
Success #stdin #stdout 0.01s 5316KB
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https://ideone.com/lRNmUe
language:
C++14 (gcc 8.3)
created:
7 hours ago
visibility:
public

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