leetcode-Intersection of Two Arrays-349

这题的意思其实是求集合的交集，就用set，之后函数返回再用vector的构造函数把set转化成vector。http://www.cnblogs.com/grandyang/p/5507129.html

class Solution {public:    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {        set<int> s(nums1.begin(), nums1.end());        set<int> ans;        for(int i=0;i<nums2.size();i++){            if(s.count(nums2[i])){                ans.insert(nums2[i]);                }        }        return vector<int>(ans.begin(), ans.end());    }};