LeetCode刷题实战290：单词规律
Given a pattern and a string s, find if s 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 s.
示例
示例1:
输入: pattern = "abba", str = "dog cat cat dog"
输出: true
示例 2:
输入:pattern = "abba", str = "dog cat cat fish"
输出: false
示例 3:
输入: pattern = "aaaa", str = "dog cat cat dog"
输出: false
示例 4:
输入: pattern = "abba", str = "dog dog dog dog"
输出: false
说明:
你可以假设 pattern 只包含小写字母， str 包含了由单个空格分隔的小写字母。
解题
public:
bool wordPattern(string pattern, string str) {
unordered_map<string, char> str2ch;
unordered_map<char, string> ch2str;
int m = str.length();
int i = 0;
for (auto ch : pattern) {
if (i >= m) {
return false;
}
int j = i;
while (j < m && str[j] != ' ') j++;
const string &tmp = str.substr(i, j - i);
if (str2ch.count(tmp) && str2ch[tmp] != ch) {
return false;
}
if (ch2str.count(ch) && ch2str[ch] != tmp) {
return false;
}
str2ch[tmp] = ch;
ch2str[ch] = tmp;
i = j + 1;
}
return i >= m;
}
};
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