Formatted question description: https://leetcode.ca/all/2032.html

# 2032. Two Out of Three (Easy)

Given three integer arrays nums1, nums2, and nums3, return a distinct array containing all the values that are present in at least two out of the three arrays. You may return the values in any order.

Example 1:

Input: nums1 = [1,1,3,2], nums2 = [2,3], nums3 = 
Output: [3,2]
Explanation: The values that are present in at least two arrays are:
- 3, in all three arrays.
- 2, in nums1 and nums2.


Example 2:

Input: nums1 = [3,1], nums2 = [2,3], nums3 = [1,2]
Output: [2,3,1]
Explanation: The values that are present in at least two arrays are:
- 2, in nums2 and nums3.
- 3, in nums1 and nums2.
- 1, in nums1 and nums3.


Example 3:

Input: nums1 = [1,2,2], nums2 = [4,3,3], nums3 = 
Output: []
Explanation: No value is present in at least two arrays.


Constraints:

• 1 <= nums1.length, nums2.length, nums3.length <= 100
• 1 <= nums1[i], nums2[j], nums3[k] <= 100

## Solution 1.

// OJ: https://leetcode.com/problems/two-out-of-three/
// Time: O(N)
// Space: O(R) where R is the range of the numbers in arrays.
class Solution {
public:
vector<int> twoOutOfThree(vector<int>& A, vector<int>& B, vector<int>& C) {
unordered_set<int> a(begin(A), end(A)), b(begin(B), end(B)), c(begin(C), end(C));
unordered_map<int, int> cnt;
for (int n : a) cnt[n]++;
for (int n : b) cnt[n]++;
for (int n : c) cnt[n]++;
vector<int> ans;
for (auto [n, c] : cnt) {
if (c >= 2) ans.push_back(n);
}
return ans;
}
};


Or

// OJ: https://leetcode.com/problems/two-out-of-three/
// Time: O(N)
// Space: O(R) where R is the range of the numbers in arrays.
class Solution {
public:
vector<int> twoOutOfThree(vector<int>& A, vector<int>& B, vector<int>& C) {
bool seen = {};
for (int n : A) seen[n] = true;
for (int n : B) seen[n] = true;
for (int n : C) seen[n] = true;
vector<int> ans;
for (int i = 1; i <= 100; ++i) {
if (seen[i] + seen[i] + seen[i] >= 2) ans.push_back(i);
}
return ans;
}
};