全排列-递增进位制数法

package permutation;

import java.util.Scanner;

public class AscendPermutation {

	// get initialization permutation of scale is number
	public String creatPermutation(int number) {
		char[] ch = new char[number];
		for (int i = 1; i <= number; ++i)
			ch[i - 1] = (char) (i + 48);
		return String.valueOf(ch);
	}

	// get interNumber 0f original permutation number
	public String getInterNumber(String permutation) {
		char[] ch = permutation.toCharArray();
		char[] save = new char[permutation.length() - 1];
		// form 2 to str.length() need to search
		for (int i = 0; i < permutation.length(); ++i) {
			if (ch[i] == '1')
				continue;
			// find the quantity of digit which right i is smaller than i
			// save is char type so make count = 48 initialization
			int j = i + 1, count = 48;
			while (j < permutation.length()) {
				if (ch[i] > ch[j]) {
					++count;
				}
				++j;
			}
			int index = permutation.length() - 2 - ((int) ch[i] - 48 - 2);
			save[index] = (char) (count);// make count to char type
		}
		return String.valueOf(save);
	}

	// next interNumber(中介数怎么翻译？)
	public String nextInterNumber(String interNumber) {
		char[] ch = interNumber.toCharArray();
		// int carry = 1;//to find the next number so initialization carry
		// equals to one
		for (int j = interNumber.length() - 1; j >= 0; --j) {
			// pow is from 2 to str.length()+1
			int pow = interNumber.length() - 1 - j + 2;
			ch[j] += 1;// denote next number or exist carry
			if (ch[j] >= pow + 48) {// ch[j] is char type
				// carry
				ch[j] = (char) (ch[j] - pow);
				// value = 1;
			} else {
				// while not exiting carry , stop the loop
				// carry = 0;
				break;
			}
		}
		return String.valueOf(ch);
	}

	// get permutation via a interNumber
	public String getPermutation(String interNumber) {
		char[] ch = interNumber.toCharArray();
		char[] npm = new char[interNumber.length() + 1];// new permutation
														// number
		// initialization of npm
		for (int i = 0; i < interNumber.length() + 1; ++i)
			npm[i] = '0';// '0' represents space
		// find the digit position form interNumber + 1 to 1
		// count spaces form right to left
		for (int i = 0; i < interNumber.length() + 1; ++i) {
			int digit = interNumber.length() + 1 - i; // need to position

			// array index out of bound
			int count = 0;// make sure count = 0 while i = interNumber.length();
			if (i < interNumber.length()) {
				count = (int) (ch[i] - 48);// char type to int type
			}
			// System.out.println("count = " + count);
			int j = interNumber.length();// from right to left traverse
			while (count > 0 && j > 0) {
				if (npm[j--] == '0') {
					--count;
				}
			}
			while (j >= 0) {
				if (npm[j] == '0') {
					npm[j] = (char) (digit + 48);// int to char
					break;
				}
				--j;
			}
		}
		return String.valueOf(npm);
	}

	public void ascendPermutationAlgorathim(String permutation) {
		int time = 0;
		// control loop stop
		while ((++time) <= factorial(permutation.length())) {
			char[] ch = permutation.toCharArray();
			//print as interNumber sequence of ascend permutation 
			for (int i = 0; i < permutation.length(); ++i) {
				System.out.print(ch[i] - 48+ " ");
//				sequence += (ch[i] - 48)*factorial((str.length() - i));
			}
			System.out.println("\t" + getInterNumber(permutation));
			permutation = getPermutation(nextInterNumber(getInterNumber(permutation)));
		}
	}

	public int factorial(int n) {
		int sum = 1;
		while (n > 1) {
			sum *= (n--);
		}
		return sum;
	}
	
///**
	public static void main(String[] args) {
		
		// TODO Auto-generated method stub
		AscendPermutation ap = new AscendPermutation();
		String per  = "83674521";
		String curInt = ap.getInterNumber(per);
		for(int j = 0 ; j < 1013 ; ++ j){
			curInt = ap.nextInterNumber(curInt);
		}
		System.out.println("curInt = " + curInt);
		 per =ap.getPermutation(curInt);
		System.out.println("per = " + per);
		Scanner scan = new Scanner(System.in);
		System.out.println("Please input scale of permutation: ");
		int scale = scan.nextInt();
		long start = System.currentTimeMillis();
		ap.ascendPermutationAlgorathim(ap.creatPermutation(scale));
		long end = System.currentTimeMillis();
		System.out.println("run time : " + (double)Math.round((end - start)/1000) + " second ");
	}
	//*/
}