leetcode605 Can Place Flowers(放置植物)

问题描述：

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.

代码：

/**
 * @param {number[]} flowerbed
 * @param {number} n
 * @return {boolean}
 */

var canPlaceFlowers = function(flowerbed, n) {
    var start = 0;
    var len = flowerbed.length;
    var num = 0;
    if(len == 1){
        return n<=(1-flowerbed[0]);
    }
    if(flowerbed[0] == 0 && flowerbed[1] == 0){
        num += 1;
        start += 1;
    }
    while(start < len){
        if(flowerbed[start]==0 && start + 1 == len-1 && flowerbed[++start] == 0){
            num+=1;
        }else if(flowerbed[start]==0 && flowerbed[start+1]==0 && flowerbed[start+2]==0){
            num++;
            start+=2;
        }else{
            start++;
        }
    }
    return num>=n;
};