LeetCode-599. Minimum Index Sum of Two Lists (JAVA)最小索引

599. Minimum Index Sum of Two Lists

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.

两个数组，寻找元素相同的并且下标相加最小的元素，如果有多个，则返回多个，两个数组各自没有重复元素

使用两个Map存储元素，然后求取最小值

public String[] findRestaurant(String[] list1, String[] list2) {
	List minRes = null;
	Map map1 = new HashMap<>();
	Map map2 = new HashMap<>();
	int min = Integer.MAX_VALUE;

	for (int i = 0; i < list1.length; i++) {
		map1.put(list1[i], i);
	}
	for (int i = 0; i < list2.length; i++) {
		map2.put(list2[i], i);
	}

	for (int i = 0; i < list1.length; i++) {
		// 如果map2包含map1的key
		if (map2.containsKey(list1[i])) {
			int sum = map1.get(list1[i]) + map2.get(list1[i]);
			if (sum < min) {
				min = sum;
				// minRes始终存储最小的sum，如果有比这个min小的sum,更新并且重置minRes
				// 多次new 了链表可以考虑在多加一个for循环，判断等于最小值的时候加入链表
				minRes = new ArrayList();
				minRes.add(list1[i]);
			} else if (sum == min) {
				minRes.add(list1[i]);
			}
		}
	}

	String[] strRes = new String[minRes.size()];
	for (int i = 0; i < minRes.size(); i++) {
		strRes[i] = minRes.get(i);
	}

	return strRes;
}