Isomorphic Strings

Posted on Edited on In Views:

205.Isomorphic Strings

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

Two strings s and t 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.

Example 1:

1
2
Input: s = "egg", t = "add"
Output: true

Example 2:

1
2
Input: s = "foo", t = "bar"
Output: false

Example 3:

1
2
Input: s = "paper", t = "title"
Output: true

哈希表：

时间复杂度：O(n)

空间复杂度：O(m)，m为字符串字符集数目

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
class Solution {
public:
	bool isIsomorphic(string s, string t) {
		unordered_map<char, char>s_t;
		unordered_map<char, char>t_s; 
		int len = s.length();
		for (int i = 0; i < len; i++) {
			char x = s[i];
			char y = t[i];
			if ((s_t.count(x) && s_t[x] != y) 
                || (t_s.count(y) && t_s[y] != x))return false;
			s_t[x] = y;
			t_s[y] = x;
		}
		return true;
	}
};