605_Can Place Flowers.md

605. 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

---

Solution:

/**
 * @param {number[]} flowerbed
 * @param {number} n
 * @return {boolean}
 */
var canPlaceFlowers = function(flowerbed, n) {
    let myFlowerBed = flowerbed
    myFlowerBed.unshift(0)
    myFlowerBed.push(0)
    
    for(let i = 1; i<=(myFlowerBed.length-2); i++){
        if(myFlowerBed[i-1]==0 && myFlowerBed[i]==0 && myFlowerBed[i+1]==0){
            myFlowerBed[i] = 1
            n--
        }
    }
    return n <= 0
};

Key Idea

• Assume that there are empty planting spots at the bourndary, both side
• The only place to plant the flower is in the middle of three consecutive's empty spots