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LeetCode solutions

1113. Moving Stones Until Consecutive II

My accepted Python solution to LeetCode problem 1113, Moving Stones Until Consecutive II, running in 14ms.

  • Difficulty: Medium
  • Python
  • Runtime 14ms
  • Memory 18.2MB

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 14ms, memory 18.2MB, accepted 2026-01-02.

python
class Solution:
    def numMovesStonesII(self, stones: List[int]) -> List[int]:
        stones.sort()
        n = len(stones)
        
        # Maximum moves: fill all gaps except one endpoint
        # Either skip first gap or skip last gap
        max_moves = max(stones[n-1] - stones[1] - n + 2, 
                       stones[n-2] - stones[0] - n + 2)
        
        # Minimum moves: use sliding window
        min_moves = n
        j = 0
        for i in range(n):
            # Find window [stones[j], stones[i]] that can fit n consecutive stones
            while stones[i] - stones[j] >= n:
                j += 1
            
            # Number of stones in window [j, i]
            window_stones = i - j + 1
            
            # Special case: if all stones in window are consecutive 
            # and we need only 1 more stone at the end
            if window_stones == n - 1 and stones[i] - stones[j] == n - 2:
                min_moves = min(min_moves, 2)
            else:
                min_moves = min(min_moves, n - window_stones)
        
        return [min_moves, max_moves]

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