Title

the problem link

Suppose Andy and Doris want to choose a restaurant for dinner, and they both have a list of favorite restaurants represented by strings.

You need to help them find out their common interest with the least list index sum. If there is a choice tie between answers, output all of them with no order requirement. You could assume there always exists an answer.

Example 1:
Input:
["Shogun", "Tapioca Express", "Burger King", "KFC"]
["Piatti", "The Grill at Torrey Pines", "Hungry Hunter Steakhouse", "Shogun"]
Output: ["Shogun"]

Explanation: The only restaurant they both like is “Shogun”.

Example 2:
Input:
["Shogun", "Tapioca Express", "Burger King", "KFC"]
["KFC", "Shogun", "Burger King"]
Output: ["Shogun"]

Explanation: The restaurant they both like and have the least index sum is “Shogun” with index sum 1 (0+1).

Note: The length of both lists will be in the range of [1, 1000]. The length of strings in both lists will be in the range of [1, 30]. The index is starting from 0 to the list length minus 1. No duplicates in both lists.

Solution

//cpp:
class Solution {
public:
	vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
		unordered_map<string, int> map1;
		for (int i = 0; i < list1.size(); i++) {
			map1[list1[i]] = i;
		}
		int index = list1.size() + list2.size();
		for (int i = 0; i < list2.size(); i++) {
			if (map1.count(list2[i])) {
				if (i + map1[list2[i]] < index)
					index = i + map1[list2[i]];
			}
		}
		vector<string> v;
		for (int i = 0; i < list2.size(); i++) {
			if (map1.count(list2[i])&& i + map1[list2[i]]==index) {
				v.push_back(list2[i]);
			}
		}
		return v;
	}
};