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

• 0217. Contains Duplicate
  • Approach
  • Python
  • C++

DONE 0217. Contains Duplicate   easy

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

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

DONE C++

#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;
  }
};