Can Place Flowers

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 = 1Output: True

Example 2:

Input: flowerbed = [1,0,0,0,1], n = 2Output: 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].

1. n is a non-negative integer which won't exceed the input array size.

判断一下相邻的元素是否为0.

代码：

        public boolean canPlaceFlowers(int[] flowerbed, int n) {        if(n == 0) return true;        if(flowerbed == null || flowerbed.length == 0) return false;        if(flowerbed.length == 1) return n<=1 && flowerbed[0] ==0;        int index = 0;        while(index<flowerbed.length) {            if(isValid(flowerbed, index)) {                if(index<flowerbed.length) {                    flowerbed[index] = 1;                    n--;                                    }            }            index++;        }        return n<=0;    }    private boolean isValid(int[] flowerbed, int index) {        if(index<0 || index>flowerbed.length-1) return false;        if(index == 0) return flowerbed[1] == 0 && flowerbed[0] == 0;        if(index == flowerbed.length-1) return flowerbed[flowerbed.length-1] == 0 && flowerbed[flowerbed.length-2] ==0;        return flowerbed[index-1]==0 && flowerbed[index]==0 && flowerbed[index+1]==0;    }