LeetCode Q205: 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.

Solution:

	class Solution {
	public:
	bool isIsomorphic(string s, string t) {
	char map_s2t[128]={'\n'};
	memset(map_s2t, '\n', sizeof(map_s2t));
	char map_t2s[128]={'\n'};
	memset(map_t2s, '\n', sizeof(map_t2s));
	if(s.length()==0)
	return true;
	for(int i=0; i<s.length(); i++){
	char schar=s[i];
	char tchar=t[i];
	if(map_s2t[schar]=='\n'&&map_t2s[tchar]=='\n'){
	map_s2t[schar]=tchar;
	map_t2s[tchar]=schar;
	continue;
	}
	if(map_s2t[schar]==tchar&&map_t2s[tchar]==schar)
	continue;
	else
	return false;
	}
	return true;
	}
	};

view raw Q205IsomorphicStrings.cpp hosted with ❤ by GitHub

Round 2 solution:

	class Solution {
	public:
	bool isIsomorphic(string s, string t) {
	if(s.length()!=t.length())
	return false;
	if(s==t||(s.empty()&&t.empty()))
	return true;
	unordered_map<int, int> myMap1;
	unordered_map<int, int> myMap2;
	for(int i=0; i<s.length(); i++){
	if(myMap1[s[i]]==0&&myMap2[t[i]]==0){
	myMap1[s[i]]=t[i];
	myMap2[t[i]]=s[i];
	}
	else
	if(myMap1[s[i]]!=t[i]||myMap2[t[i]]!=s[i])
	return false;
	}
	return true;
	}
	};

view raw Q205Rnd2.cpp hosted with ❤ by GitHub