# [205. Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/)

## 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.

**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.




## 题目大意

这道题和第 290 题基本是一样的。第 290 题是模式匹配，这道题的题意是字符串映射，实质是一样的。

给定一个初始字符串串，判断初始字符串是否可以通过字符映射的方式，映射到目标字符串，如果可以映射，则输出 true，反之输出 false。

## 解题思路

这道题做法和第 290 题基本一致。


## 代码

```go

package leetcode

func isIsomorphic(s string, t string) bool {
	strList := []byte(t)
	patternByte := []byte(s)
	if (s == "" && t != "") || (len(patternByte) != len(strList)) {
		return false
	}

	pMap := map[byte]byte{}
	sMap := map[byte]byte{}
	for index, b := range patternByte {
		if _, ok := pMap[b]; !ok {
			if _, ok = sMap[strList[index]]; !ok {
				pMap[b] = strList[index]
				sMap[strList[index]] = b
			} else {
				if sMap[strList[index]] != b {
					return false
				}
			}
		} else {
			if pMap[b] != strList[index] {
				return false
			}
		}
	}
	return true
}

```