[leetcode]290.Word Pattern

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題目

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.

解法思路

用一個hashmap將pattern和str進行依次<key,value>映射即可。

代碼

class Solution {    public boolean wordPattern(String pattern, String str) {        String[] arr = str.split(" ");        if(pattern.length() != arr.length)            return false;                        HashMap<Character, String> map = new HashMap<>();        for(int i = 0; i < pattern.length(); i++) {            if(map.containsKey(pattern.charAt(i))) {                if(!map.get(pattern.charAt(i)).equals(arr[i]))                    return false;            }            else {                if(!map.containsValue(arr[i]))                    map.put(pattern.charAt(i),arr[i]);                else                     return false;            }        }        return true;    }}

[leetcode]290.Word Pattern