N位数打印

 转载请注明作者与出处：franciscolv http://www.cnblogs.com/franciscolv/archive/2011/11/20/2255834.html

 N位数打印需要注意越界问题。考虑到int或long的范围有界，所以采用字符数组的方式去打印。这里注意打印的时候每固定个值换行便于查看。

package SortSet;

/**
 * 打印N位数
 * 
 * @author franciscolv
 * 
 */
public class NPrint {
    private static int count =0;
    public static void main(String[] args) {
        print(10);
    }

    public static void print(int n) {
        if (n <= 0)
            return;
        char[] c = new char[n];
        for (int i = 0; i < 10; i++) {
            c[0] = (char) (i + '0');
            print0(c, n, 0);
        }
    }

    private static void print0(char[] c, int len, int n) {
        if (n == len - 1) {
            print1(c);
            return;
        }
        for (int i = 0; i < 10; i++) {
            c[n + 1] = (char) ('0' + i);
            print0(c, len, n + 1);
        }

    }

    private static void print1(char[] c) {
        boolean isZero = true;
        for (int i = 0; i < c.length; i++) {
            if (isZero && c[i] != '0')
                isZero = false;
            if (!isZero)
                System.out.print(c[i]);
                
        }
        count++;
        if(count%50==0) 
            System.out.println();
        else
            System.out.print(" ");
    }
}