from typing import List class Solution: def canCross(self, stones: List[int]) -> bool: if stones[1] != 1: return False n = len(stones) dp = [[False] * n for _ in range(n)] dp[0][0] = True for i in range(1, n): for j in range(0, i): k = stones[i] - stones[j] if k < 1 or k > j + 1: continue dp[i][k] = dp[j][k - 1] or dp[j][k] or dp[j][k + 1] if i == n - 1 and dp[i][k]: return True return False