605. Can Place Flowers.java

E
tags: Array, Greedy
time: O(n)
space: O(1)

#### Array
- just check flowerbed[i-1] & flowerbed[i+1] and count

```
/*
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.
*/

/*
    Greedy,just check flowerbed[i-1] and move on
*/
class Solution {
    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        if (flowerbed.length == 0 || n <= 0) return true;
        int m = flowerbed.length;
        for (int i = 0; i < m; i++) {
            if (flowerbed[i] == 1) continue;
            int lastVal = i == 0 ? 0 : flowerbed[i-1];
            int nextval = i == m-1? 0: flowerbed[i+1];
            if (lastVal == 0 && nextval == 0) {
                flowerbed[i] = 1;
                n--;
            }
            if (n <= 0) return true;
        }
            
        return false;
    }
}
```