Formatted question description: https://leetcode.ca/all/605.html
605. Can Place Flowers (Easy)
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]
is0
or1
.- There are no two adjacent flowers in
flowerbed
. 0 <= n <= flowerbed.length
Similar Questions:
Solution 1.
A placeable plot should be empty, as well as its direct neighbors, if any. So, go through the flowerbed, whenever you find a placeable plot, place the flower into it, decrement n
. Finally, return n == 0
.
// OJ: https://leetcode.com/problems/can-place-flowers
// Time: O(N)
// Space: O(N)
class Solution {
public:
bool canPlaceFlowers(vector<int>& A, int n) {
for (int i = 0; i < A.size() && n > 0; ++i) {
if (A[i] == 1) continue;
if ((i == 0 || A[i - 1] == 0) && (i == A.size() - 1 || A[i + 1] == 0)) {
A[i] = 1;
--n;
}
}
return n == 0;
}
};
Java
class Solution {
public boolean canPlaceFlowers(int[] flowerbed, int n) {
List<Integer> emptyCounts = new ArrayList<Integer>();
int prevEmpty = -1;
int emptyCount = 1;
int length = flowerbed.length;
for (int i = 0; i <= length; i++) {
int num = i < length ? flowerbed[i] : 0;
if (num == 0) {
emptyCount++;
prevEmpty = i;
} else {
if (emptyCount > 0) {
emptyCounts.add(emptyCount);
emptyCount = 0;
}
}
}
if (emptyCount > 0)
emptyCounts.add(emptyCount);
int maxFlowers = 0;
for (int num : emptyCounts)
maxFlowers += (num - 1) / 2;
return maxFlowers >= n;
}
}