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

含义：这道题给了我们一个01数组，其中1表示已经放了花，0表示可以放花的位置，但是有个限制条件是不能有相邻的花。为给定的n朵花能否放置完毕

解法1

    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        int count = 0;
        for(int i = 0; i < flowerbed.length && count < n; i++) {
            if(flowerbed[i] == 0) {
         //get next and prev flower bed slot values. If i lies at the ends the next and prev are considered as 0. 
               int next = (i == flowerbed.length - 1) ? 0 : flowerbed[i + 1]; 
               int prev = (i == 0) ? 0 : flowerbed[i - 1];
               if(next == 0 && prev == 0) {
                   flowerbed[i] = 1;
                   count++;
               }
            }
        }
        
        return count == n;
    }

解法2

       if (n == 0) return true;
        if (flowerbed.length == 0) return false;
        if (flowerbed.length == 1) {
            if (flowerbed[0] == 1) {
                return false;
            }
            return n > 1 ? false : true;
        }
        if (flowerbed.length == 2) {
            if (n == 1) {
                if (flowerbed[0] + flowerbed[1] == 0) return true;
                return false;
            }
            return false;
        }
        if (flowerbed[0] + flowerbed[1] == 0) {
            flowerbed[0] = 1;
            n--;
        }
        for (int i = 1; i <= flowerbed.length - 2; i++) {
            if (flowerbed[i - 1] + flowerbed[i] + flowerbed[i + 1] == 0) {
                flowerbed[i] = 1;
                n--;
            }
        }

        if (n > 0) {
            if (flowerbed[flowerbed.length - 2] + flowerbed[flowerbed.length - 1] == 0) {
                flowerbed[flowerbed.length - 1] = 1;
                n--;
            }
        }

        return n > 0 ? false : true;