leetcode-605-easy

Can Place Flowers

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.

Given an integer array flowerbed containing 0's and 1's, where 0 means empty and 1 means not empty, and an integer n, 
return if n new flowers can be planted in the flowerbed 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
Constraints:

1 <= flowerbed.length <= 2 * 104
flowerbed[i] is 0 or 1.
There are no two adjacent flowers in flowerbed.
0 <= n <= flowerbed.length

思路一：检测数组是否存在三个连续的 0，如果存在，说明可以种下一朵花，注意数组开头和结尾需要特殊处理

    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        int[] secondFlowerbed = new int[flowerbed.length + 2];
        System.arraycopy(flowerbed, 0, secondFlowerbed, 1, flowerbed.length);

        for (int i = 1; i < flowerbed.length - 1; i++) {
            if (flowerbed[i] == 0 && flowerbed[i - 1] == 0 && flowerbed[i + 1] == 0) {
                n--;
                i += 1;
            }

            if (n <= 0) {
                break;
            }
        }

        return n <= 0;
    }