# [LeetCode] 290. Word Pattern 词语模式

Given a pattern and a string str, find if str follows the same pattern.

Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.

Example 1:

Input: pattern = "abba", str = "dog cat cat dog"
Output: true

Example 2:

Input:pattern = "abba", str = "dog cat cat fish"
Output: false

Example 3:

Input: pattern = "aaaa", str = "dog cat cat dog"
Output: false

Example 4:

Input: pattern = "abba", str = "dog dog dog dog"
Output: false

Notes:
You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.

Credits:
Special thanks to @minglotus6 for adding this problem and creating all test cases.

class Solution {
public:
bool wordPattern(string pattern, string str) {
unordered_map<char, string> m;
istringstream in(str);
int i = 0, n = pattern.size();
for (string word; in >> word; ++i) {
if (i >= n) continue;
if (m.count(pattern[i])) {
if (m[pattern[i]] != word) return false;
} else {
for (auto a : m) {
if (a.second == word) return false;
}
m[pattern[i]] = word;
}
}
return i == n;
}
};

class Solution {
public:
bool wordPattern(string pattern, string str) {
unordered_map<char, int> m1;
unordered_map<string, int> m2;
istringstream in(str);
int i = 0, n = pattern.size();
for (string word; in >> word; ++i) {
if (i == n || m1[pattern[i]] != m2[word]) return false;
m1[pattern[i]] = m2[word] = i + 1;
}
return i == n;
}
};

Github 同步地址：

https://github.com/grandyang/leetcode/issues/290

Isomorphic Strings

Word Pattern II

https://leetcode.com/problems/word-pattern/

https://leetcode.com/problems/word-pattern/discuss/73402/8-lines-simple-Java

https://leetcode.com/problems/word-pattern/discuss/73409/Short-C%2B%2B-read-words-on-the-fly

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posted @ 2015-10-06 13:21  Grandyang  阅读(14367)  评论(10编辑  收藏  举报