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Easy
Contains Duplicate
Given an integer array `nums`, return `true` if any value appears at least twice in the array, and return `false` if every element is distinct. This problem tests your ability to use a Hash Set to track seen elements and optimize lookups.
Examples
Input:nums = [1,2,3,1]
Output:true
The element 1 appears twice in the array.
Input:nums = [1,2,3,4]
Output:false
All elements are distinct.
Constraints
1 <= nums.length <= 10^5-10^9 <= nums[i] <= 10^9
Approach
Use two nested loops to compare every element with every other element in the array. If any two elements are equal, we found a duplicate.
Complexity Analysis
Time Complexity
O(n^2)
Space Complexity
O(1)
This approach is highly inefficient and will likely result in a Time Limit Exceeded (TLE) error for large arrays.
Solution.java
class Solution { public boolean containsDuplicate(int[] nums) { // Compare each element with every other element for (int i = 0; i < nums.length; i++) { for (int j = i + 1; j < nums.length; j++) { if (nums[i] == nums[j]) { return true; // Found a duplicate } } } return false; // No duplicates found }}