leetcode 349. Intersection of Two Arrays

class Solution {public:    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {        sort(nums1.begin(),nums1.end());        sort(nums2.begin(),nums2.end());        int a = 0,b = 0;        vector<int> ans;        while(a < nums1.size() && b < nums2.size()){            if(nums1[a] == nums2[b]){                if(ans.size() ==0 || ans.back() != nums1[a]) ans.push_back(nums1[a]);                a++,b++;            }            else if(nums1[a] > nums2[b]) b++;            else a++;        }        return ans;    }};