Skip to main content

2032 - Two Out of Three (Easy)

https://leetcode.com/problems/two-out-of-three

Problem Statement​

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 = [3]
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 = [5]
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

Approach 1: Hash Map​

Written by @wingkwong
class Solution {
public:
    vector<int> twoOutOfThree(vector<int>& nums1, vector<int>& nums2, vector<int>& nums3) {
        vector<int> ans;
        // use hash map to all elements from nums1, nums2, and nums3
        map<int, int> m;
        for(auto x : nums1) m[x] = 1;
        for(auto x : nums2) m[x] = 1;
        for(auto x : nums3) m[x] = 1;
        for(auto x : m) {
            // for each element in hash map, check if it exists in nums1, nums2, and nums3
            int c1 = 0, c2 = 0, c3 = 0;
            if (find(nums1.begin(), nums1.end(), x.first) != nums1.end()) c1 = 1;
            if (find(nums2.begin(), nums2.end(), x.first) != nums2.end()) c2 = 1;
            if (find(nums3.begin(), nums3.end(), x.first) != nums3.end()) c3 = 1;
            // if it presents in at least two out of the three arrays,
            // then add it to ans
            if (c1 + c2 + c3 >= 2) ans.push_back(x.first);
        }
        return ans;
    }
};