LeetCode Can Place Flowers

LeetCode 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.

今天第一次做Leetcode的weekly contest,AC了三题,最后一题看起来好繁琐,没A。

第一题,简单贪心即可,从第0个位置开始,检查每个位置的前后是否为1,如果不为1,说明该位置可以种花,填上1,最后统计新填上的1的个数和n的关系。

代码如下:

class Solution {
public:
	bool canPlaceFlowers(vector<int>& flowerbed, int n) {
		int m = flowerbed.size();
		for (int i = 0; i < m; ++i) {
			if (flowerbed[i] == 0) {
				if (i - 1 >= 0 && flowerbed[i - 1] == 1)continue;
				if (i + 1 < m&&flowerbed[i + 1] == 1)continue;
				flowerbed[i] = 1;
				--n;
			}
		}
		return n <= 0;
	}
};

本代码提交AC,用时26MS。

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