290. Word Pattern(easy)

Easy

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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 strcontains lowercase letters that may be separated by a single space.

 

C++：

/*
 * @Author: SourDumplings
 * @Date: 2019-09-06 10:34:12
 * @Link: https://github.com/SourDumplings/
 * @Email: changzheng300@foxmail.com
 * @Description: https://leetcode.com/problems/word-pattern/
 */

class Solution
{
public:
    bool wordPattern(string pattern, string str)
    {
        istringstream is(str);
        map<char, string> m1;
        map<string, char> m2;
        for (auto &&c : pattern)
        {
            string s;
            if (is.eof())
            {
                return false;
            }

            is >> s;
            if (m1.find(c) == m1.end())
            {
                if (m2.find(s) == m2.end())
                {
                    m1[c] = s;
                    m2[s] = c;
                }
                else
                {
                    return false;
                }
            }
            else if (m1[c] != s)
            {
                return false;
            }
        }
        if (is.eof())
        {
            return true;
        }
        return false;
    }
};

Java：

import java.util.Hashtable;
import java.util.Map;

/*
 * @Author: SourDumplings
 * @Date: 2019-09-06 10:46:09
 * @Link: https://github.com/SourDumplings/
 * @Email: changzheng300@foxmail.com
 * @Description: https://leetcode.com/problems/word-pattern/
 */

class Solution
{
    public boolean wordPattern(String pattern, String str)
    {
        Map<Character, String> m1 = new Hashtable<>();
        Map<String, Character> m2 = new Hashtable<>();
        String[] sA = str.split(" ");
        int l = pattern.length();
        if (l != sA.length)
        {
            return false;
        }
        for (int i = 0; i < l; i++)
        {
            String s = sA[i];
            Character c = pattern.charAt(i);
            if (!m1.containsKey(c))
            {
                if (!m2.containsKey(s))
                {
                    m1.put(c, s);
                    m2.put(s, c);
                }
                else
                {
                    return false;
                }
            }
            else if (!m1.get(c).equals(s))
            {
                return false;
            }
        }
        return true;
    }
}