Duplicates

中文说明

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Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, and it should return false if every element is distinct.

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Example 1

Input: [1,2,3,1]
Output: true

Example 2

Input: [1,2,3,4]
Output: false

Example 3

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true

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Answer Here

/**
 * @author Loucianus
 */
public class Duplicates {

    public boolean containsDuplicatebyHashSet(int[] nums) {
        HashSet<Integer> set = new HashSet<Integer>();
        for (int i = 0; i < nums.length; i++) {
            if (!set.add(nums[i])) return true;
        }
        return false;
    }
}

Thinking

• Use properties of the set.

in-space: O(n)
in-time : O(n)