leetcode 605 Can Place Flowers

题目详情

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.

将一个由0，1组成的数组想象成一行花圃，值为1代表当前位置已经种植了花，值为0表示未种植。为了保证花朵的营养，不能在相邻的地方种植花朵。题目输入一个数组和一个n值，求当前花圃能否种植下n朵花，可以的话返回true，不可以则返回false。

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

思路

• 大体思路就是判断当前位置前后的元素是否都为0，如果都为0，则满足种植条件，找出符合条件的位置有几个就可以。
• 需要注意的是特殊情况的考虑，如第一个元素和最后一个元素只有一个相邻元素。

解法

    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        int count = 0;
        for(int i=0;i<flowerbed.length && count < n;i++){
            if(flowerbed[i] == 0){
                int prev = (i == 0) ? 0 : flowerbed[i-1];
                int next = (i == flowerbed.length-1) ? 0 : flowerbed[i+1];
                if(prev == 0 && next == 0){
                    flowerbed[i] = 1;
                    count ++;
                    
                }
            }
        }
        
        return count == n;
    }