Problem
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.
Solution: Greedy
Time complexity: O(n)
Space complexity: O(1)
C++
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// Author: Huahua // Running time: 21 ms class Solution { public: bool canPlaceFlowers(vector<int>& flowerbed, int n) { int count = 0; for (size_t i = 0; i < flowerbed.size() && count < n; ++i) { if (flowerbed[i]) continue; bool left = i == 0 ? true : !flowerbed[i - 1]; bool right = i == flowerbed.size() - 1 ? true : !flowerbed[i + 1]; if (left && right) { flowerbed[i++] = 1; ++count; } } return count == n; } }; |
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