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LeetCode solutions

2651. Count Ways to Group Overlapping Ranges

My accepted Python solution to LeetCode problem 2651, Count Ways to Group Overlapping Ranges, running in 19ms.

  • Difficulty: Medium
  • Python
  • Runtime 19ms
  • Memory 45.7MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 19ms, memory 45.7MB, accepted 2025-12-31.

python
class Solution:
    def countWays(self, ranges: List[List[int]]) -> int:
        MOD = 10**9 + 7
        
        # Sort ranges by start time
        ranges.sort()
        
        # Merge overlapping ranges to count independent groups
        groups = 0
        current_end = -1
        
        for start, end in ranges:
            if start > current_end:
                # New group
                groups += 1
                current_end = end
            else:
                # Extend current group
                current_end = max(current_end, end)
        
        # Each group can go to either group 1 or group 2
        # Answer is 2^groups
        return pow(2, groups, MOD)

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