**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]