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LeetCode solutions

1120. Flower Planting With No Adjacent

My accepted Python solution to LeetCode problem 1120, Flower Planting With No Adjacent, running in 34ms.

  • Difficulty: Medium
  • Python
  • Runtime 34ms
  • Memory 22MB

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 34ms, memory 22MB, accepted 2026-01-02.

python
class Solution:
    def gardenNoAdj(self, n: int, paths: List[List[int]]) -> List[int]:
        # Build adjacency list
        graph = [[] for _ in range(n + 1)]
        for x, y in paths:
            graph[x].append(y)
            graph[y].append(x)
        
        result = [0] * (n + 1)
        
        for garden in range(1, n + 1):
            # Find colors used by neighbors
            used_colors = set()
            for neighbor in graph[garden]:
                if result[neighbor] != 0:
                    used_colors.add(result[neighbor])
            
            # Choose first available color
            for color in range(1, 5):
                if color not in used_colors:
                    result[garden] = color
                    break
        
        return result[1:]

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