605. 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 = 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.
找出前一个和后一个，看是不是0，如果是0的话就可以放啦，注意处理两边的情况。

public class Solution {
public boolean canPlaceFlowers(int[] flowerbed, int n) {
if(flowerbed == null || flowerbed.length == 0){
return false;
}
if(n == 0){
return true;
}
for(int i=0; i<flowerbed.length; i++){
if(flowerbed[i] == 0){
int pre = (i == 0 ? 0 : flowerbed[i-1]);
int next = (i == flowerbed.length - 1 ? 0 : flowerbed[i+1]);
if(pre+next == 0){
flowerbed[i] = 1;
n--;
}
if(n==0){
return true;
}
}
}
return false;
}
}