Problem:
Write a method to compute all permutations of a string.
Solution:
Let’s assume a given string S represented by the letters A1, A2, A3, ... , An
To permute set S, we can select the first character, A1, permute the remainder of the string to get a new list. Then, with that new list, we can “push” A1 into each possible position.
For example, if our string is “abc”, we would do the following:
1. Let first = “a” and let remainder = “bc”
2. Let list = permute(bc) = {“bc”, “cd”}
3. Push “a” into each location of “bc” (--> “abc”, “bac”, “bca”) and “cb” (--> “acb”, “cab”, “cba”)
4. Return our new list
Complexity: O(n!)
Code:
Another approach:
With Repeated characters in the input string:
In a loop,a particular character must be swapped with current index only once,
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Showing posts with label Permutation of string. Show all posts
Showing posts with label Permutation of string. Show all posts
Tuesday, July 19, 2011
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