Class Permutation

Synopsis of Enum Permutation

public enum Permutation { 
    /*
     * Utilities (5)
     */
        static int[] random(int n); 
        static int[] increasing(int n); 
        static int[] decreasing(int n); 
        static void swap(int[] a, int i, int j); 
        static long factorial(short n); 
} 

Code

// SSDLPedia
package il.ac.technion.cs.ssdl.utils;

import static il.ac.technion.cs.ssdl.utils.DBC.nonnegative;
import static il.ac.technion.cs.ssdl.utils.DBC.require;
import il.ac.technion.cs.ssdl.stereotypes.Utility;

import java.util.Random;

/**
 * A collection of utility function to generate permutations.
 * 
 * Author: Yossi Gil,
 * See:  19/06/2008
 */
@Utility public enum Permutation {
    ;
    /**
     * n a non-negative integer
     * Return: a random permutation of length n, represented as an array.
     */
    public static int[] random(final int n) {
        nonnegative(n);
        final int[] $ = increasing(n);
        final Random r = new Random(System.nanoTime());
        for (int i = 0; i < n; i++)
            swap($, i, r.nextInt(n));
        return $;
    }
    
    /**
     * n a non-negative integer
     * Return: the increasing permutation of length n, represented as an array.
     */
    public static int[] increasing(final int n) {
        nonnegative(n);
        final int[] $ = new int[n];
        for (int i = 0; i < n; i++)
            $[i] = i;
        return $;
    }
    
    /**
     * n a non-negative integer
     * Return: the decreasing permutation of length n, represented as an array.
     */
    public static int[] decreasing(final int n) {
        nonnegative(n);
        final int[] $ = new int[n];
        for (int i = 0; i < n; i++)
            $[i] = n - 1 - i;
        return $;
    }
    
    /**
     * Swap the contents of two int array cells
     * 
     * a the array with two cells to be swapped
     * i index of this first array cell
     * j index of the second array cell
     */
    public static void swap(final int[] a, final int i, final int j) {
        nonnegative(i);
        nonnegative(j);
        require(i < a.length);
        require(j < a.length);
        if (i == j)
            return;
        final int temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }
    
    /**
     * Compute the factorial of a small integer
     * 
     * n a given integer
     * Return: the factorial of n
     */
    public static long factorial(final short n) {
        if (n <= 1)
            return 1;
        return n * factorial((short) (n - 1));
    }
}

Metrics

Metric	Value	Acronym	Explanation
LOC	86	Lines Of Code	Total number of lines in the code
SCC	35	SemiColons Count	Total number of semicolon tokens found in the code.
NOT	382	Number Of Tokens	Comments, whitespace and text which cannot be made into a token not included.
VCC	1621	Visible Characters Count	The total number of non-white (i.e., not space, tab, newline, carriage return, form feed) characters.
CCC	911	Code Characters Count	Total number of non-white characters in tokens. White space characters in string and character literals are not counted.
UIC	31	Unique Identifiers Count	The number of different identifiers found in the code
WHC	3	Weighted Horizontal Complexity	A heuritistic on horizontal complexity

Statistics

Statitic	Value
Average token length	2.4
Tokens/line	4.4
Visible characters/line	19
Code characters/line	11
Semicolons/tokens	9%
Comment text percentage	43%

Tokens by kind

Token Kind	Occurrences
KEYWORD	67
OPERATOR	26
LITERAL	7
ID	120
PUNCTUATION	162
COMMENT	7
OTHER	180