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:

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.

題意：

給定一個花圃（1代表已種有花，0表示空）， 規定花不能相鄰。 問新來的n束花能否被種到該花圃。

Solution1： Greedy

掃給定數組，只要滿足條件就插個1（種朵花）， 直到n==0(新來花都種下了) 或者數組掃完。

明顯的，掃到一個坑為0， 且其左邊為0，右邊為0， 該坑就可以種花

同時註意左右邊界的特殊處理， （1）如果該坑為front， 且其右邊為0， 該坑可以種花

（2）如果該坑為tail， 且其左邊為0， 該坑可以種花

code

 1
 
 class Solution {
 2     public boolean canPlaceFlowers(int[] flowerbed, int n) {  
 3         int i = 0;
 4         while( i < flowerbed.length && n > 0 ){
 5             if (flowerbed[i]==0 && (i==0 || flowerbed[i-1]==0) &&  (i==flowerbed.length-1 || flowerbed[i+1]==0)){
 6                 flowerbed [i] = 1;
 7                 n--;
 8             }
 9             i++;
10         }
11         return n == 0;
12     }
13 }

[leetcode]605. Can Place Flowers能放花嗎