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.
Example 1:
Input: s = "egg", t = "add"
Output: true
Example 2:
Input: s = "foo", t = "bar"
Output: false
Example 3:
Input: s = "paper", t = "title"
Output: true
Note:
You may assume both s and t have the same length.
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Approach #1
Time: O(N) && Space: O(N)
classSolution {publicbooleanisIsomorphic(String s,String t) {int[] m1 =newint[256];int[] m2 =newint[256];int n =s.length();for (int i =0; i < n; i++) {if (m1[s[i]] != m2[t[i]]) {returnfalse; } m1[s[i]] = i +1; m2[t[i]] = i +1; }returntrue; }}
Approach #2 HashMap
classSolution {publicbooleanisIsomorphic(String s,String t) {if (s ==null||s.length() <=1) returntrue;HashMap<Character,Character> map =newHashMap<Character,Character>();for (int i =0; i <s.length(); i++) {char a =s.charAt(i);char b =t.charAt(i);if (map.containsKey(a)) {if (map.get(a).equals(b)) {continue; } else {returnfalse; } } else {if (!map.containsValue(b)) {map.put(a, b); } else {returnfalse; } } }returntrue; }}