350. Intersection of Two Arrays II
不会做!!
没想法,小的set?
1.需要记住顺序,
2.长短不固定,
假设短的是长的子集?直接拼接成字符串?
大佬答案:
class Solution {
public:
vector<int> intersect(vector<int>& nums1, vector<int>& nums2) {
unordered_map<int, int> dict;
vector<int> res;
for(int i = 0; i < (int)nums1.size(); i++) dict[nums1[i]]++;
for(int i = 0; i < (int)nums2.size(); i++)
if(dict.find(nums2[i]) != dict.end() && --dict[nums2[i]] >= 0) res.push_back(nums2[i]);
return res;
}
};
这个好:
C++
vector<int> intersect(vector<int>& a, vector<int>& b) {
sort(a.begin(), a.end());
sort(b.begin(), b.end());
a.erase(set_intersection(a.begin(), a.end(), b.begin(), b.end(), a.begin()), a.end());
return a;
}
Another:
vector<int> intersect(vector<int>& a, vector<int>& b) {
unordered_map<int, int> ctr;
for (int i : a)
ctr[i]++;
vector<int> out;
for (int i : b)
if (ctr[i]-- > 0)
out.push_back(i);
return out;
}
class Solution {
public:
vector<int> intersect(vector<int>& nums1, vector<int>& nums2) {
vector<int> res;
std::sort(nums1.begin(),nums1.end());
std::sort(nums2.begin(),nums2.end());
std::set_intersection(nums1.begin(),nums1.end(),nums2.begin(),nums2.end(),insert_iterator<vector<int>>(res,res.begin()));
return res; // res:2,2
}
};