[LeetCode]Isomorphic Strings

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic.

Two strings are isomorphic if the characters in s can be replaced to get t.

All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

For example,
Given "egg", "add", return true.

Given "foo", "bar", return false.

Given "paper", "title", return true.

Note:
You may assume both s and t have the same length.

Hash Table，由于No two characters may map to the same character but a character may map to itself.

判断完s->t和t->s即可。

class Solution {
public:
    bool isIsomorphic(string s, string t) {
        unordered_map<char,char> showed;
        for(int i=0;i<s.length();i++)
        {
            if(showed.find(s[i])!=showed.end())
            {
                if(showed[s[i]]!=t[i])
                {
                    return false;
                }
            }
            else
            {
                showed[s[i]]=t[i];
            }
        }
        showed.clear();
        for(int i=0;i<s.length();i++)
        {
            if(showed.find(t[i])!=showed.end())
            {
                if(showed[t[i]]!=s[i])
                {
                    return false;
                }
            }
            else
            {
                showed[t[i]]=s[i];
            }
        }
        return true;
    }
};