Java Integer Array Permutation nextPermutation(int[] arr)

Description

next Permutation

License

Open Source License

Parameter

Parameter	Description
arr	a parameter

Declaration

public static int[] nextPermutation(int[] arr) 

Method Source Code

//package com.java2s;

public class Main {
    /**//from ww  w .j  a  va 2 s.  c  o  m
     * @param arr
     * @return
     */
    public static int[] nextPermutation(int[] arr) {
        int[] a = (int[]) arr.clone();
        int n = a.length - 1;
        int j = n - 1;
        // "123, 132, 213, 231, 312, 321"
        while (a[j] > a[j + 1]) {
            if (j == 0) {
                // last permutation - reset
                int[] error = new int[] { 0 };
                return error;
            }
            j--;
        }

        // j is the largest subscript with a[j] < a[j+1]
        int k = n;
        while (a[j] > a[k]) {
            // sanity checking here
            k--;
        }
        // a[k] is the smallest term greater than a[j] to the
        // right of a[j] -- swap a[j] and a[k]
        int tmp = a[j];
        a[j] = a[k];
        a[k] = tmp;
        int r = n;
        int s = j + 1;

        while (r > s) {
            // swap a[r] and a[s]
            tmp = a[r];
            a[r] = a[s];
            a[s] = tmp;
            r--;
            s++;
        }

        return a;
    }
}

Related

1. nextPermutation(int v)
2. nextPermutation(int[] is)
3. nextPermutation(int[] next)
4. nextPermutation(int[] nums)