217. Contains Duplicate

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217. Contains Duplicate

Description

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.

Example 1:

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Input: nums = [1,2,3,1]

Output: true

Explanation:

The element 1 occurs at the indices 0 and 3.

Example 2:

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Input: nums = [1,2,3,4]

Output: false

Explanation:

All elements are distinct.

Example 3:

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Input: nums = [1,1,1,3,3,4,3,2,4,2]

Output: true

Constraints:

  • 1 <= nums.length <= 10^5
  • -10^9 <= nums[i] <= 10^9

Hints/Notes

  • 2025/01/02
  • set
  • No solution from 0x3F

Solution

Language: C++

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class Solution {
public:
    bool containsDuplicate(vector<int>& nums) {
        unordered_set<int> s;
        for (auto& num : nums) {
            if (s.contains(num)) {
                return true;
            }
            s.insert(num);
        }
        return false;
    }
};