288. Unique Word Abbreviation

方法1:
方法2:
- 易错点

An abbreviation of a word follows the form . Below are some examples of word abbreviations:

a) it                      --> it    (no abbreviation)1↓
b) d|o|g                   --> d1g1    1  11---5----0----5--8↓   ↓    ↓    ↓  ↓
c) i|nternationalizatio|n  --> i18n11---5----0↓   ↓    ↓
d) l|ocalizatio|n          --> l10n

Assume you have a dictionary and given a word, find whether its abbreviation is unique in the dictionary. A word’s abbreviation is unique if no other word from the dictionary has the same abbreviation.

Example:

Given dictionary = [ “deer”, “door”, “cake”, “card” ]

isUnique(“dear”) -> false
isUnique(“cart”) -> true
isUnique(“cane”) -> false
isUnique(“make”) -> true

方法1:

思路：

在constructor的时候就要把单词都存成hashmap, 那么value是什么呢？如果只对应着缩写对应单词的数量将不能区分door, door和door，deer。前一个是unique，后一个不是。还是要用一个set来记住所有单词，加上set本身有去重的功能，查询的时候只需要返回s.size()。

class ValidWordAbbr {public:ValidWordAbbr(vector<string> dictionary) {for (auto d: dictionary){if (d.size() < 3){hash[d].insert(d);}else {string abrev = *d.begin() + to_string(d.size() - 2) + *(d.end() - 1);hash[abrev].insert(d);}}}bool isUnique(string word) {int count = 0;string abrev;if (word.size() < 3) {abrev = word;}else {abrev = *word.begin() + to_string(word.size() - 2) + *(word.end() - 1);}for (auto w: hash[abrev]){if (w != word) count ++;}return count == 0;}
private:unordered_map<string, set<string>> hash;
};/*** Your ValidWordAbbr object will be instantiated and called as such:* ValidWordAbbr obj = new ValidWordAbbr(dictionary);* bool param_1 = obj.isUnique(word);*/

方法2:

思路：

为了压缩空间，同时还能区分同缩写单词是否是同单词，用了"消消乐" 的方法：value只保存unique的单词，如果在construct阶段进来的单词不同，两个词都消掉，设为“”。注意这个设置是有讲究的：它保证了count ！= 0，同时又unqualified both。保证count ！= 0是因为，之后的isValid可能会询问之前不存在的缩写，应该算作unique。

易错点

消掉并恢复“”
自己不应该消掉自己：[“a”, “a”]，“a” is still unique。
isValid要检查未出现过的缩写

class ValidWordAbbr {public:ValidWordAbbr(vector<string> dictionary) {for (auto d: dictionary){string abrev;if (d.size() < 3){abrev = d;}else {abrev= *d.begin() + to_string(d.size() - 2) + *(d.end() - 1);}if (hash.count(abrev) == 0 || hash[abrev] == d) {hash[abrev] = d;}else {hash[abrev] = "";}}}bool isUnique(string word) {string abrev;if (word.size() < 3) {abrev = word;}else {abrev = *word.begin() + to_string(word.size() - 2) + *(word.end() - 1);}return hash.count(abrev) == 0 || hash[abrev] == word;}
private:unordered_map<string, string> hash;
};/*** Your ValidWordAbbr object will be instantiated and called as such:* ValidWordAbbr obj = new ValidWordAbbr(dictionary);* bool param_1 = obj.isUnique(word);*/

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288. Unique Word Abbreviation

288. Unique Word Abbreviation

方法1:

方法2:

易错点

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