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1153. String Transforms Into Another String (Hard)

Given two strings str1 and str2 of the same length, determine whether you can transform str1 into str2 by doing zero or more conversions.

In one conversion you can convert all occurrences of one character in str1 to any other lowercase English character.

Return true if and only if you can transform str1 into str2.

 

Example 1:

Input: str1 = "aabcc", str2 = "ccdee"
Output: true
Explanation: Convert 'c' to 'e' then 'b' to 'd' then 'a' to 'c'. Note that the order of conversions matter.

Example 2:

Input: str1 = "leetcode", str2 = "codeleet"
Output: false
Explanation: There is no way to transform str1 to str2.

 

Note:

1. 1 <= str1.length == str2.length <= 10^4
2. Both str1 and str2 contain only lowercase English letters.

Related Topics

[Hash Table] [String]

Hints

Hint 1

Model the problem as a graph problem. Add an edge from one character to another if you need to convert between them.

Hint 2

What if one character needs to be converted into more than one character?

Hint 3

There would be no solution. Thus, every node can have at most one outgoing edge.

Hint 4

How to process a linked list?

Hint 5

How to process a cycle?

Hint 6

What if there is a character with no outgoing edge? You can use it to break all cycles!