algorithm notes: leetcode#605 can place flowers

class :
    def canPlaceFlowers(self, flowerbed, n):
        """
        :type flowerbed: List[int]
        :type n: int
        :rtype: bool
        """
        cnt = 0
        p0 = p1 = -2
        for i, val in enumerate(flowerbed+[0]):
            if val:
                p1 = i
            else:
                p0 = i
                if p0 - p1 > 2:
                    cnt += 1
                    p1 = i - 1
        return cnt >= n

class :
    def canPlaceFlowers(self, flowerbed, n):
        """
        :type flowerbed: List[int]
        :type n: int
        :rtype: bool
        """
        left = n
        p0 = p1 = -2
        for i, val in enumerate(flowerbed+[0]):
            if val:
                p1 = i
            else:
                p0 = i
                if p0 - p1 > 2:
                    left -= 1
                    p1 = i - 1
                if left == 0:
                    return True
        return False

class :
    def canPlaceFlowers(self, flowerbed, n):
        """
        :type flowerbed: List[int]
        :type n: int
        :rtype: bool
        """
        cnt = 0
        flowerbed = [0] + flowerbed + [0]
        for i in range(1, len(flowerbed)-1):
            if flowerbed[i] == flowerbed[i-1] == flowerbed[i+1] == 0:
                flowerbed[i] = 1
                cnt += 1
        return cnt >= n