Day 54

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class Solution:
    def countTrapezoids(self, points: List[List[int]]) -> int:
        MOD = 10**9 + 7
        from collections import defaultdict
        
        y_groups = defaultdict(int)
        for x, y in points:
            y_groups[y] += 1
        
        seg_counts = []
        for k in y_groups.values():
            if k >= 2:
                seg_counts.append(k*(k-1)//2 % MOD)
        
        if len(seg_counts) < 2:
            return 0
        
        seg_counts.sort()
        
        total = 0
        prefix = 0
        for v in seg_counts:
            total = (total + v * prefix) % MOD
            prefix = (prefix + v) % MOD
        
        return total % MOD