575. Distribute Candies

Description

Alice has n candies, where the ith candy is of type candyType[i]. Alice noticed that she started to gain weight, so she visited a doctor.

The doctor advised Alice to only eat n / 2 of the candies she has (n is always even). Alice likes her candies very much, and she wants to eat the maximum number of different types of candies while still following the doctor's advice.

Given the integer array candyType of length n, return the maximum number of different types of candies she can eat if she only eats n / 2 of them.

 

Example 1:

Input: candyType = [1,1,2,2,3,3]
Output: 3
Explanation: Alice can only eat 6 / 2 = 3 candies. Since there are only 3 types, she can eat one of each type.

Example 2:

Input: candyType = [1,1,2,3]
Output: 2
Explanation: Alice can only eat 4 / 2 = 2 candies. Whether she eats types [1,2], [1,3], or [2,3], she still can only eat 2 different types.

Example 3:

Input: candyType = [6,6,6,6]
Output: 1
Explanation: Alice can only eat 4 / 2 = 2 candies. Even though she can eat 2 candies, she only has 1 type.

 

Constraints:

• n == candyType.length
• 2 <= n <= 104
• n is even.
• -105 <= candyType[i] <= 105

Solutions

Solution 1: Hash Table

We use a hash table to store the types of candies. If the number of candy types is less than $n / 2$, then the maximum number of candy types that Alice can eat is the number of candy types. Otherwise, the maximum number of candy types that Alice can eat is $n / 2$.

The time complexity is $O(n)$, and the space complexity is $O(n)$. Where $n$ is the number of candies.

Python3JavaC++GoTypeScript

class Solution:
    def distributeCandies(self, candyType: List[int]) -> int:
        return min(len(candyType) >> 1, len(set(candyType)))

class Solution {
    public int distributeCandies(int[] candyType) {
        Set<Integer> s = new HashSet<>();
        for (int c : candyType) {
            s.add(c);
        }
        return Math.min(candyType.length >> 1, s.size());
    }
}

class Solution {
public:
    int distributeCandies(vector<int>& candyType) {
        unordered_set<int> s(candyType.begin(), candyType.end());
        return min(candyType.size() >> 1, s.size());
    }
};

func distributeCandies(candyType []int) int {
    s := hashset.New()
    for _, c := range candyType {
        s.Add(c)
    }
    return min(len(candyType)>>1, s.Size())
}

function distributeCandies(candyType: number[]): number {
    const s = new Set(candyType);
    return Math.min(s.size, candyType.length >> 1);
}

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