[LeetCode] Problem 605 - Can Place Flowers

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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

No.1

Input: flowerbed = [1,0,0,0,1], n = 1

Output: True

No.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.

Code

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

        if (prev + next == 0) {
            n--;
            flowerbed[i] = 1;
        }
    }

    return n == 0;
}