Time: 91 ms (29.84%), Space: 67.6 MB (10.41%) - LeetHub

Author: hogan-tech

3623-count-number-of-trapezoids-i/3623-count-number-of-trapezoids-i.py

@@ -0,0 +1,33 @@
+# time complexity: O(n)
+# space complexity: O(n)
+from collections import defaultdict
+from typing import List
+from math import comb
+
+MOD = 10**9 + 7
+
+
+class Solution:
+    def countTrapezoids(self, points: List[List[int]]) -> int:
+        yPoints = defaultdict(list)
+        for x, y in points:
+            yPoints[y].append(x)
+
+        pairsPerY = []
+        for y in yPoints:
+            m = len(yPoints[y])
+            if m >= 2:
+                count = comb(m, 2)
+                pairsPerY.append(count)
+
+        sumPairs = sum(pairsPerY)
+        sumSquares = sum(count * count for count in pairsPerY)
+        total = (sumPairs * sumPairs - sumSquares) // 2
+
+        return total % MOD
+
+
+points = [[1, 0], [2, 0], [3, 0], [2, 2], [3, 2]]
+print(Solution().countTrapezoids(points))
+points = [[0, 0], [1, 0], [0, 1], [2, 1]]
+print(Solution().countTrapezoids(points))