LeetCode 605. Can Place Flowers

Description

https://leetcode.com/problems/can-place-flowers/

You have a long flowerbed in which some of the plots are planted, and some are not. However, flowers cannot be planted in adjacent plots.

Given an integer array flowerbed containing 0‘s and 1‘s, where 0 means empty and 1 means not empty, and an integer n, return if n new flowers can be planted in the flowerbed without violating the no-adjacent-flowers rule.

Example 1:

Input: flowerbed = [1,0,0,0,1], n = 1
Output: true

Example 2:

Input: flowerbed = [1,0,0,0,1], n = 2
Output: false

Constraints:

  • 1 <= flowerbed.length <= 2 * 104
  • flowerbed[i] is 0 or 1.
  • There are no two adjacent flowers in flowerbed.
  • 0 <= n <= flowerbed.length

Explanation

Iterate the flowerbed list, and each 0 position, check if can place a flower. In all, checking if n number of flowers can be placed.

Python Solution

class Solution:
    def canPlaceFlowers(self, flowerbed: List[int], n: int) -> bool:
        
        i = 0
        while i < len(flowerbed):
            if n == 0:
                return True
            
            if flowerbed[i] == 0:
                if i == len(flowerbed) - 1:                    
                    if flowerbed[i - 1] != 1:             
                        flowerbed[i] = 1
                        n -= 1
                elif i == 0:                    
                    if flowerbed[i + 1] != 1:             
                        flowerbed[i] = 1
                        n -= 1
                else:
                    if flowerbed[i - 1] != 1 and flowerbed[i + 1] != 1:             
                        flowerbed[i] = 1
                        n -= 1                    
            
            
            i += 1
            
        return n == 0
  • Time Complexity: O(N).
  • Space Complexity: O(1).

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