Leetcode350. Intersection of Two Arrays II很簡單的做法

Given two arrays, write a function to compute their intersection.

Example:
Given nums1 = [1, 2, 2, 1], nums2 = [2, 2], return [2, 2].

Note:

• Each element in the result should appear as many times as it shows in both arrays.
• The result can be in any order.

Follow up:

• What if the given array is already sorted? How would you optimize your algorithm?
• What if nums1's size is small compared to nums2's size? Which algorithm is better?
• What if elements of nums2 are stored on disk, and the memory is limited such that you cannot load all elements into the memory at once?

class Solution {
public:
    vector<int> intersect(vector<int>& nums1, vector<int>& nums2) {
        std::sort(nums1.begin(), nums1.end());
        std::sort(nums2.begin(), nums2.end());
        
        std::vector<int> vec;
        int i1 = 0;
        int i2 = 0;
        
        while (i1 < nums1.size() && i2 < nums2.size())
        {
            if (nums1[i1] < nums2[i2]) {
                i1++;
            } else if (nums1[i1] > nums2[i2]) {
                i2++;
            } else {
                vec.push_back(nums1[i1]);
                i1++;
                i2++;
            }
        }
        return vec;
    }
};