cpp-flashcards/org/study_deck_02/dsa/arrays-hashing/0217-contains-duplicate.org

#+PROPERTY: STUDY_DECK_02
* DONE 0217. Contains Duplicate :easy:
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*0217. Contains Duplicate][0217. Contains Duplicate]]
:END:

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:*

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

*Output:* true

*Explanation:*

The element 1 occurs at the indices 0 and 3.

*Example 2:*

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

*Output:* false

*Explanation:*

All elements are distinct.

*Example 3:*

*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}~

** DONE Approach
Write your approach here.

** DONE Python
#+begin_src python
class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        s = set()
        for x in nums:
            if x in s:
                return True
            s.add(x)
        return False
#+end_src

** DONE C++
#+begin_src cpp
#include <vector>
#include <set>
class Solution {
public:
  bool containsDuplicate(std::vector<int>& nums) {
    std::set<int> s;
    for (int x: nums) {
      if (s.contains(x)) {
        return true;
      }
      s.insert(x);
    }
    return false;
  }
};
#+end_src