Printing from 1 to prove safety offer the maximum number of bits n

Subject description:

Enter the number n, the maximum print from 1 to n-bit decimal order. For example, input 3, then print out up to a maximum of 1, 2, 3 digits 999.

 

Analysis: Note that can not directly enter the maximum n-bit decimal number, as may belong to a large number, this number can not therefore need to represent a string or a long long int storage.

 

Ideas: we are all aligned solution with n bits, each bit can be a number from 0 to 9. Recursive solution. Note that the leading 0 Do not output, such as a print only when the 1-9, 1-9 2 when printing (instead of 01, ...), 10-99.

 

 1 #include <iostream>
 2 #include <algorithm> 
 3 #include <cstdio>
 4 #include <cstring>
 5 using namespace std;
 6 void Print1ToMaxOfNDigitsRecursively(char* number, int length, int index);
 7 
 8 void PrintNumber(char* number) {
 9     int index = 0;
10     bool isBeginning0 = true;
11     int nlength = strlen(number);
12      // index to the left of the first index is not zero. Of particular note is the entire string are all zero 
13 is      for ( int I = 0 ; I <nlength; I ++ ) {
 14          IF (! Number [I] = ' 0 ' ) {
 15              index = I;
 16              BREAK ;
 . 17          }
 18 is      }
 . 19      IF ((index ==! 0 && Number [index] == ' 0 ' {))
 20 is          for ( int I = index; I <nlength; I ++ ) {
 21 is              the printf ("%c", number[i]);
22         }
23         printf("\n");
24     }
25 }
26 
27 void Print1ToMaxOfNDigits(int n) {
28     if (n <= 0) {
29         return;
30     }
31     char *number = new char[n + 1];
32     number[n] = '\0';
33     for (int i = 0; i < 10; i++) {
34         number[0] = i + '0';
35         Print1ToMaxOfNDigitsRecursively(number, n, 0);
36     }
37     delete [] number;
38 }
39 
40 void Print1ToMaxOfNDigitsRecursively(char* number, int length, int index) {
41     if (index == length - 1) {
42         PrintNumber(number);
43         return;
44     }
45     for (int i = 0; i < 10; i++) {
46         number[index + 1] = i + '0';
47         Print1ToMaxOfNDigitsRecursively(number, length, index + 1);
48     }
49 }
50 
51 int main() {
52     int number;
53     while (cin >> number) {
54         Print1ToMaxOfNDigits(number);
55     }
56     return 0;
57 }