LeetCode#349 Intersection of Two Arrays

来源：互联网发布：支持ubuntu的手机编辑：程序博客网时间：2024/06/07 22:07

key: map–find & count
Runtime: 16 ms / beats 19.77%
No reference

class Solution {public:    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {        vector<int> res;        map<int, int> map1, map2, mapInset;        for(int i = 0; i < nums1.size(); i++)        {            map<int, int>::iterator iter;            iter = map1.find(nums1[i]);            if(iter == map1.end())            {                map1.insert(pair<int, int>(nums1[i],1));            }            else                iter->second++;        }        for(int i = 0; i < nums2.size(); i++)        {            // map<int, int>::iterator iter;            // iter = map1.find(nums2[i]);            int cnt1 = map1.count(nums2[i]);            // if(iter == map1.end()) continue;            if(cnt1 == 0) continue;            else            {                // map<int, int>::iterator iter2;                // iter2 = mapInset.find(nums2[i]);                int cnt2 = mapInset.count(nums2[i]);                //if(iter == mapInset.end())                if(cnt2 == 0)                {                    mapInset.insert(pair<int, int>(nums2[i],1));                    res.push_back(nums2[i]);                }                else                    continue;            }        }        return res;    }};

Update: unordered set & for range
Runtime: 8 ms / beats 85.44%
Reference: discuss

class Solution {public:    vector<int> intersection(vector<int>& nums1, vector<int>& nums2) {        unordered_set<int> set1(nums1.begin(), nums1.end());        vector<int> res;        for(auto iter : nums2)        {            if(set1.count(iter))            {                res.push_back(iter);                set1.erase(iter);            }        }        return res;    }};

0 0