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

除了開頭和結尾的特殊情況外，在中間要種花，都需要有三個空位。因此設定變數empty來計數空位，當達到3時，可以插入一朵花，並且empty變為1。而在開頭和結尾處，則需要兩個空位就能放花，注意[0，0，0，0，1]，這一類情況。AC碼：

public class Solution {
    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        if(n==1&&flowerbed.length==1&&flowerbed[0]==0)return true;
        int empty=0
 
;
        int canflower=0;
        for(int i=0;i<flowerbed.length;i++){
            if(flowerbed[i]==0){
                empty++;
                if(empty==3){
                    canflower++;
                    empty=1;
                }
                if(((i==flowerbed.length-1)||(i==1))&&empty>=2){
                    canflower++;
                    empty=1;
                }
            }else{
                empty=0;
            }
        }
        if(canflower>=n)return true;
        return false;
    }
}