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98 lines
1.9 KiB
Markdown
98 lines
1.9 KiB
Markdown
# [290. Word Pattern](https://leetcode.com/problems/word-pattern/)
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## 题目
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Given a pattern and a string str, find if str follows the same pattern.
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Here follow means a full match, such that there is a bijection between a letter in pattern and a non-empty word in str.
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**Example 1**:
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```
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Input: pattern = "abba", str = "dog cat cat dog"
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Output: true
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```
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**Example 2**:
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```
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Input:pattern = "abba", str = "dog cat cat fish"
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Output: false
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```
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**Example 3**:
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```
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Input: pattern = "aaaa", str = "dog cat cat dog"
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Output: false
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```
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**Example 4**:
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```
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Input: pattern = "abba", str = "dog dog dog dog"
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Output: false
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```
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**Note**:
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You may assume pattern contains only lowercase letters, and str contains lowercase letters separated by a single space.
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## 题目大意
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给定一个模式串，判断字符串是否和给定的模式串，是一样的模式。
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## 解题思路
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这道题用 2 个 map 即可。1 个 map 记录模式与字符串的匹配关系，另外一个 map 记录字符串和模式的匹配关系。为什么需要记录双向的关系呢？因为 Example 4 中，a 对应了 dog，这个时候 b 如果再对应 dog 是错误的，所以这里需要从 dog 查询它是否已经和某个模式匹配过了。所以需要双向的关系。
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## 代码
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```go
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package leetcode
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import "strings"
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func wordPattern(pattern string, str string) bool {
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strList := strings.Split(str, " ")
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patternByte := []byte(pattern)
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if pattern == "" || len(patternByte) != len(strList) {
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return false
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}
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pMap := map[byte]string{}
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sMap := map[string]byte{}
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for index, b := range patternByte {
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if _, ok := pMap[b]; !ok {
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if _, ok = sMap[strList[index]]; !ok {
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pMap[b] = strList[index]
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sMap[strList[index]] = b
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} else {
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if sMap[strList[index]] != b {
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return false
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}
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}
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} else {
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if pMap[b] != strList[index] {
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return false
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}
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}
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}
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return true
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}
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``` |