题目
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.
答案
class Solution {
public boolean isIsomorphic(String s, String t) {
if(s.length() != t.length()) return false;
Map m = new HashMap<>();
Set set = new HashSet<>();
for(int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
Character cm = m.get(c);
if(cm != null) {
if(t.charAt(i) != cm) return false;
}
else {
if(set.contains(t.charAt(i))) return false;
m.put(c, t.charAt(i));
set.add(t.charAt(i));
}
}
return true;
}
}