Leetcode: Can Place Flowers

Can Place Flowers

Similar Problems:

Suppose 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 – they would compete for water and both would die.

Given a flowerbed (represented as an array containing 0 and 1, where 0 means empty and 1 means not empty), and a number n, return if n new flowers can be planted in it 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


  1. The input array won’t violate no-adjacent-flowers rule.
  2. The input array size is in the range of [1, 20000].
  3. n is a non-negative integer which won’t exceed the input array size.

Github: code.dennyzhang.com

Credits To: leetcode.com

Leave me comments, if you have better ways to solve.

## Blog link: https://code.dennyzhang.com/can-place-flowers
## Basic Ideas: Find consecutive 0s
##              For a range of n 0s
##                  If the range in the middle, we can place (n-1)/2 flowers
##              Add a virtual '0' to the head, add a virtual '0' and '1' to the end
## Complexity: Time O(n), Space O(1)
class Solution(object):
    def canPlaceFlowers(self, flowerbed, n):
        :type flowerbed: List[int]
        :type n: int
        :rtype: bool
        total_flower, counter = 0, 0
        length = len(flowerbed)
        for i in range(-1, length+2):
            if i == -1 or i == length: num = 0
            elif i == length + 1:
                num = 1
                num = flowerbed[i]

            # caculate how many flowers we can plant
            if num == 0: counter += 1
            else: total_flower, counter = total_flower + (counter-1)/2, 0
        return total_flower >= n

# s = Solution()
# s = s.canPlaceFlowers([0,0,1,0,1], 1) # true

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