Candy There are n
children standing in a line. Each child is assigned a rating value given in the integer array ratings
.
You are giving candies to these children subjected to the following requirements:
- Each child must have at least one candy.
- Children with a higher rating get more candies than their neighbors.
Return the minimum number of candies you need to have to distribute the candies to the children.
Example 1:
Input: ratings = [1,0,2] Output: 5 Explanation: You can allocate to the first, second and third child with 2, 1, 2 candies respectively.
Example 2:
Input: ratings = [1,2,2] Output: 4 Explanation: You can allocate to the first, second and third child with 1, 2, 1 candies respectively. The third child gets 1 candy because it satisfies the above two conditions.
Constraints:
n == ratings.length
1 <= n <= 2 * 104
0 <= ratings[i] <= 2 * 104
Candy Solutions
✅Time: O(n)
✅Space: O(n)
C++
class Solution {
public:
int candy(vector<int>& ratings) {
const int n = ratings.size();
int ans = 0;
vector<int> l(n, 1);
vector<int> r(n, 1);
for (int i = 1; i < n; ++i)
if (ratings[i] > ratings[i - 1])
l[i] = l[i - 1] + 1;
for (int i = n - 2; i >= 0; --i)
if (ratings[i] > ratings[i + 1])
r[i] = r[i + 1] + 1;
for (int i = 0; i < n; ++i)
ans += max(l[i], r[i]);
return ans;
}
};
Java
class Solution {
public int candy(int[] ratings) {
final int n = ratings.length;
int ans = 0;
int[] l = new int[n];
int[] r = new int[n];
Arrays.fill(l, 1);
Arrays.fill(r, 1);
for (int i = 1; i < n; ++i)
if (ratings[i] > ratings[i - 1])
l[i] = l[i - 1] + 1;
for (int i = n - 2; i >= 0; --i)
if (ratings[i] > ratings[i + 1])
r[i] = r[i + 1] + 1;
for (int i = 0; i < n; ++i)
ans += Math.max(l[i], r[i]);
return ans;
}
}
Python
class Solution:
def candy(self, ratings: List[int]) -> int:
n = len(ratings)
ans = 0
l = [1] * n
r = [1] * n
for i in range(1, n):
if ratings[i] > ratings[i - 1]:
l[i] = l[i - 1] + 1
for i in range(n - 2, -1, -1):
if ratings[i] > ratings[i + 1]:
r[i] = r[i + 1] + 1
for a, b in zip(l, r):
ans += max(a, b)
return ans
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