599. Minimum Index Sum of Two Lists

• Difficulty: Easy

• Topics: Hash Table

• Similar Questions:

  • Intersection of Two Linked Lists

Problem:

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:

Solutions:

class Solution {
public:
    vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
        unordered_map<string, int> restaurantIndex;
        for (int i = 0; i < list1.size(); ++i) {
            restaurantIndex[list1[i]] = i;
        }

        int minSum = INT_MAX;
        vector<string> ret;
        for (int i = 0; i < list2.size(); ++i) {
            if (restaurantIndex.count(list2[i]) > 0) {
                int index1 = restaurantIndex[list2[i]];
                if (i + index1 < minSum) {
                    minSum = i + index1;
                    ret = {list2[i]};
                } else if (i + index1 == minSum) {
                    ret.push_back(list2[i]);
                }
            }
        }

        return ret;
    }
};