# Word Pattern Problem

## Description

LeetCode Problem 290.

Given a pattern and a string s, find if sfollows 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.

Example 1:

``````1
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Input: pattern = "abba", s = "dog cat cat dog"
Output: true
``````

Example 2:

``````1
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Input: pattern = "abba", s = "dog cat cat fish"
Output: false
``````

Example 3:

``````1
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Input: pattern = "aaaa", s = "dog cat cat dog"
Output: false
``````

Example 4:

``````1
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Input: pattern = "abba", s = "dog dog dog dog"
Output: false
``````

Constraints:

• 1 <= pattern.length <= 300
• pattern contains only lower-case English letters.
• 1 <= s.length <= 3000
• s contains only lower-case English letters and spaces ‘ ‘.
• s does not contain any leading or trailing spaces.
• All the words in s are separated by a single space.

## Sample C++ Code

``````1
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class Solution {
public:
bool wordPattern(string pattern, string str) {
int i = 0, j = 0;
map<char, string> ht;
map<string, char> ht2;
bool match = true;
string s;

while (!str.empty()) {
size_t p = str.find(' ');
int len = str.size();
s = str.substr(0, p);
str = str.substr(p+1, len-p-1);

if (pattern.size() < i+1) {
match = false;
break;
}

if (ht.find(pattern[i]) == ht.end()) {
if (ht2.find(s) != ht2.end()) {
match = false;
break;
}
ht[pattern[i]] = s;
ht2[s] = pattern[i];
} else {
if (ht[pattern[i]] != s) {
match = false;
break;
}
}
i ++;
if (p == -1) {
if (i < pattern.size()) {
match = false;
}
break;
}
}

return match;
}
};
``````