leetcode 205. 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.

注意看清题目

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

accept