LeetCode_205. Isomorphic Strings

205. Isomorphic Strings

Easy

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.

package leetcode.easy;

import java.util.HashMap;

public class IsomorphicStrings {
	public boolean isIsomorphic(String s, String t) {
		if (s.length() != t.length()) {
			return false;
		}
		HashMap<Character, Character> map = new HashMap<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 {
					return false;
				}
			} else {
				if (!map.containsValue(b)) {
					map.put(a, b);
				} else {
					return false;
				}
			}
		}
		return true;
	}

	@org.junit.Test
	public void test() {
		String s1 = "egg";
		String t1 = "add";
		String s2 = "foo";
		String t2 = "bar";
		String s3 = "paper";
		String t3 = "title";
		System.out.println(isIsomorphic(s1, t1));
		System.out.println(isIsomorphic(s2, t2));
		System.out.println(isIsomorphic(s3, t3));
	}
}