Objective: Write an algorithm to Print All the Well Ordered Permutations of a Given String.
What is Well Ordered String: When all the alphabets in a string occur in the increasing order irrespective of Lower Case or Upper case.
http://www.careercup.com/question?id=6206517812396032
Example :
"Sumit" - Not Well Ordered . 'u' occurred after 'S'. "Now" - Well Ordered. N<o<W. Input: Interview Output: [e, e, I, i, n, r, t, v, w] [e, e, i, I, n, r, t, v, w] [e, e, i, I, n, r, t, v, w] [e, e, I, i, n, r, t, v, w]
Approach:
- Get the input string.
- Find out all the permutations of a String.
- Before printing check if the permutation is well formed.
Code:
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| import java.util.Arrays; | |
| public class WellFormedStrings { | |
| // Logic: | |
| // 1. Get the input sequence | |
| // 2. Find out all the permutations of a String | |
| // 3. Before printing if the permutation is well formed. | |
| char[] A; | |
| public void wellFormedString(String S) { | |
| A = S.toCharArray(); | |
| permutation(A, 0); | |
| } | |
| public void permutation(char[] A, int left) { | |
| if (left == A.length) { | |
| if (isWellFormed(A)) { | |
| System.out.println(Arrays.toString(A)); | |
| } | |
| return; | |
| } | |
| for (int i = left; i < A.length; i++) { | |
| swap(i, left); | |
| permutation(A, left + 1); | |
| swap(i, left); // backtrack | |
| } | |
| } | |
| public void swap(int a, int b) { | |
| char temp = A[a]; | |
| A[a] = A[b]; | |
| A[b] = temp; | |
| } | |
| public boolean isWellFormed(char[] A) { | |
| boolean wellFormed = true; | |
| for (int i = 0; i < A.length – 1; i++) { | |
| if (Character.toLowerCase(A[i]) > Character.toLowerCase(A[i + 1])) { | |
| wellFormed = false; | |
| break; | |
| } | |
| } | |
| return wellFormed; | |
| } | |
| public static void main(String[] args) { | |
| String S = "Interview"; | |
| System.out.println("Given String – " + S); | |
| WellFormedStrings i = new WellFormedStrings(); | |
| i.wellFormedString(S); | |
| } | |
| } |
Output:
Given String - Interview [e, e, I, i, n, r, t, v, w] [e, e, i, I, n, r, t, v, w] [e, e, i, I, n, r, t, v, w] [e, e, I, i, n, r, t, v, w]