205. 判断两个字符串的模式是否相同 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.

Note:
You may assume both s and t have the same length.

public class Solution {
    public bool IsIsomorphic(string s, string t) {
		if (s.Length != t.Length) {
			return false;
		}
		Dictionary<char, int> set = new Dictionary<char, int>();
		List<int> parS = new List<int>();
		int num = 1;
		foreach(var i in s) {
			int val;
			set.TryGetValue(i, out val);
			if (val != 0) {
				parS.Add(set[i]);
			} else {
				set[i] = num;
				parS.Add(set[i]);
				num++;
			}
		}
		List<int> parT = new List<int>();
		set.Clear();
		num = 1;
		foreach (var i in t) {
			int val;
			set.TryGetValue(i, out val);
			if (val != 0) {
				parT.Add(set[i]);
			} else {
				set[i] = num;
				parT.Add(set[i]);
				num++;
			}
		}
		for (var i = 0; i < parS.Count; i++) {
			if (parT[i] != parS[i]) {
				return false;
			}
		}
		return true;
    }
}

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