题目

完善程序：矩形计数（接上题）。 #include <iostream> using namespace std; struct point { int x, y, id; }; bool equals(point a, point b) { return a.x == b.x && a.y == b.y; } bool cmp(point a, point b) { return ①; } void sort(point A[], int n) { for (int i = 0; i < n; i++) for (int j = 1; j < n; j++) if (cmp(A[j], A[j - 1])) { point t = A[j]; A[j] = A[j - 1]; A[j - 1] = t; } } int unique(point A[], int n) { int t = 0; for (int i = 0; i < n; i++) if (②) A[t++] = A[i]; return t; } bool binary_search(point A[], int n, int x, int y) { point p; p.x = x; p.y = y; p.id = n; int a = 0, b = n - 1; while (a < b) { int mid = ③; if (④) a = mid + 1; else b = mid; } return equals(A[a], p); } const int MAXN = 1000; point A[MAXN]; int main() { int n; cin >> n; for (int i = 0; i < n; i++) { cin >> A[i].x >> A[i].y; A[i].id = i; } sort(A, n); n = unique(A, n); int ans = 0; for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) if (⑤ && binary_search(A, n, A[i].x, A[j].y) && binary_search(A, n, A[j].x, A[i].y)) { ans++; } cout << ans << endl; return 0; } ④处应填（ ）