599. Minimum Index Sum of Two 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:

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

思路：

Solution (C++):

vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
    int m = list1.size(), n = list2.size();
    int min_index = INT_MAX;
    vector<string> res;        
    unordered_map<string, int> hash;
    
    for (int i = 0; i < m; ++i) {
        hash.emplace(list1[i], i);
    }
    
    for (int i = 0; i < n; ++i) {
        if (hash.count(list2[i]) == 0)  continue;
        
        int sum = i + hash[list2[i]];
        
        if (sum < min_index)  res.clear();
        
        if (sum <= min_index) {
            res.push_back(list2[i]);
            min_index = sum;
        }
    }
    return res;
}

性能：

Runtime: 120 ms  Memory Usage: 25.8 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB