PROBLEM:
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
.
Examples:
- pattern =
"abba"
, str ="dog cat cat dog"
should return true. - pattern =
"abba"
, str ="dog cat cat fish"
should return false. - pattern =
"aaaa"
, str ="dog cat cat dog"
should return false. - pattern =
"abba"
, str ="dog dog dog dog"
should return false.
Notes:
You may assume pattern
contains only lowercase letters, and str
contains lowercase letters separated by a single space.
SOLVE:
bool wordPattern(string pattern, string str) { map<char, int> p2i; map<string, int> w2i; istringstream in(str); int i = 0, n = pattern.size(); for (string word; in >> word; ++i) { if (i == n || p2i[pattern[i]] != w2i[word]) return false; p2i[pattern[i]] = w2i[word] = i + 1; } return i == n; }
注:这题主要让自己熟练 C++ STL 中的 map 容器运用。