Given two string arrays words1 and words2, return the number of strings that appear exactly once in each of the two arrays.
Example 1:
Input: words1 = ["leetcode","is","amazing","as","is"], words2 = ["amazing","leetcode","is"]
Output: 2
Explanation:
- "leetcode" appears exactly once in each of the two arrays. We count this string.
- "amazing" appears exactly once in each of the two arrays. We count this string.
- "is" appears in each of the two arrays, but there are 2 occurrences of it in words1. We do not count this string.
- "as" appears once in words1, but does not appear in words2. We do not count this string.
Thus, there are 2 strings that appear exactly once in each of the two arrays.
Example 2:
Input: words1 = ["b","bb","bbb"], words2 = ["a","aa","aaa"]
Output: 0
Explanation: There are no strings that appear in each of the two arrays.
Example 3:
Input: words1 = ["a","ab"], words2 = ["a","a","a","ab"]
Output: 1
Explanation: The only string that appears exactly once in each of the two arrays is "ab".
Constraints:
1 <= words1.length, words2.length <= 1000
1 <= words1[i].length, words2[j].length <= 30
words1[i] and words2[j] consists only of lowercase English letters.
统计出现过一次的公共字符串。
给你两个字符串数组 words1 和 words2 ，请你返回在两个字符串数组中 都恰好出现一次 的字符串的数目。
思路
用两个 hashmap map1 和 map2 分别记录 words1 和 words2 中每个不同单词的出现次数。遍历 map1 中的 keySet，如果 keySet 中的单词在 words1 和 words2 中均只出现一次，则这是一个符合题意的公共字符串。
复杂度
时间O(n)
空间O(n)
代码
Java实现
class Solution {
public int countWords(String[] words1, String[] words2) {
HashMap<String, Integer> map1 = new HashMap<>();
for (String word : words1) {
map1.put(word, map1.getOrDefault(word, 0) + 1);
}
HashMap<String, Integer> map2 = new HashMap<>();
for (String word : words2) {
map2.put(word, map2.getOrDefault(word, 0) + 1);
}
int count = 0;
for (String word : map1.keySet()) {
int val = map1.get(word);
if (val == 1 && map2.containsKey(word) && map2.get(word) == 1) {
count++;
}
}
return count;
}
}
- Occurrence LeetCode Common Count Wordsoccurrence leetcode common count characters leetcode formed words leetcode greatest divisor common leetcode ancestor common binary unreachable undirected leetcode count leetcode target count pairs communicate leetcode servers count leetcode number count pairs leetcode strings ranges count leetcode average subtree count