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.

解答

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public class Solution {
	public String[] findRestaurant(String[] list1, String[] list2) {
		HashMap<Integer, List<String>> map = new HashMap<>();
		for (int i = 0; i < list1.length; i++) {
			for (int j = 0; j < list2.length; j++) {
				if (list1[i].equals(list2[j])) {
					if (!map.containsKey(i + j)) {
						map.put(i + j, new ArrayList<String>());
					}
					map.get(i + j).add(list1[i]);
				}
			}
		}
		int minsum = Integer.MAX_VALUE;
		for (int i : map.keySet()) {
			minsum = Math.min(minsum, i);
		}
		String[] res = new String[map.get(minsum).size()];
		return map.get(minsum).toArray(res);
	}
}