How to use a Java HashSet by example
What is a HashSet
A HashSet
is an unordered collection containing unique elements. It has the standard collection operations Add, Remove, Contains, but since it uses a hash-based implementation, these operations are O(1)
Learn with a Programming Question
Given an integer array with even length, where different numbers in this array represent different kinds of candies. Each number means one candy of the corresponding kind. You need to distribute these candies equally in number to brother and sister. Return the maximum number of kinds of candies the sister could gain.
Example 1:
Example 2:
Note:
- The length of the given array is in range [2, 10,000], and will be even.
- The number in given array is in range [-100,000, 100,000].
The Solution using a HashSet
// Our class
class Solution {
// Our method call
public int distributeCandies(int[] candies) {
// Use a HashSet to store all the intergers
HashSet<Integer> set = new HashSet<>();
// for each candy
for (int candy: candies) {
// add it to the set
set.add(candy);
}
// Return the minimum between the size and half the length
return Math.min(set.size(), candies.length / 2);
}
}