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:

1. The input array won't violate no-adjacent-flowers rule.
2. The input array size is in the range of [1, 20000].
3. n is a non-negative integer which won't exceed the input array size.

我的答案:

class Solution {
    public boolean canPlaceFlowers(int[] flowerbed, int n) {
        List<Integer> list = new ArrayList<>();
		for (int i = 0; i < flowerbed.length; i++) {
			if(flowerbed[i] == 1){
				list.add(i);
			}
		}
		if(list.size()==0 ){
			n = n-(flowerbed.length+1)/2;
			return n<=0;
		}
		//head
		Integer head = list.get(0);
		if(head>1){
			n = n-head/2;
		}
		//tail
		Integer tail = list.get(list.size()-1);
		if(flowerbed.length-tail-1>1){
			n = n-(flowerbed.length-tail-1)/2;
		}
		
		for(int i = 0;i<list.size()-1;i++){
			int begin = list.get(i);
			int end = list.get(i+1);
			if(end-begin>2){
				n = n-(end-begin-2)/2;
			}
		}
		
		return n <= 0;
    }
}

大牛的答案:

public boolean canPlaceFlowers(int[] flowerbed, int n) {
    int count = 1;
    int result = 0;
    for(int i=0; i<flowerbed.length; i++) {
        if(flowerbed[i] == 0) {
            count++;
        }else {
            result += (count-1)/2;
            count = 0;
        }
    }
    if(count != 0) result += count/2;
    return result>=n;
}