剑指offer——面试题17：打印从1到最大的n位数

用字符串模拟加法：

 #include"iostream"
 #include"string.h"
 using namespace std;
 
 bool AddOne(char *number,int n);
 void PrintNumber(char *number,int n);
 
 void Print1ToN(int n)
 {
     if(n<=)
         return;
     char *number=new char[n+];
     memset(number,'',n);
     number[n]='\0';
     while(AddOne(number,n))
     {
         PrintNumber(number,n);
     }
     delete[] number;
 }
 
 bool AddOne(char *number,int n)
 {
     bool isInRange=true;
     int carry=;
     int iDigit;
     for(int i=n-;i>=;i--)
     {
         iDigit=number[i]-''+carry;
         if(i==n-)
             iDigit++;
         if(iDigit>=)
         {
             if(i==)
                 isInRange=false;
             else
             {
                 carry=iDigit/;
                 iDigit%=;
                 number[i]=iDigit+'';
             }
         }
         else
         {
             number[i]=iDigit+'';
             break;
         }
     }
     return isInRange;
 }
 
 void PrintNumber(char *number,int n)
 {
     bool firstNoZero=false;
     for(int i=;i<n;i++)
     {
         if(!firstNoZero&&number[i]!='')
         {
             firstNoZero=true;
         }
         if(firstNoZero)
             cout<<number[i];
     }
     cout<<endl;
 }
 int main()
 {
     int n;
     while(cin>>n)
     {
         Print1ToN(n);
     }
     return ;
 }

还可以用全排列的思想，递归调用去解决：

 #include"iostream"
 using namespace std;
 
 void Print1ToNRecursively(int *number,int length,int index);
 void PrintNumber(int *number,int n);
 
 void Print1ToN(int n)
 {
     int *number=new int[n];
 
     for(int i=;i<;i++)
     {
         number[]=i;
         Print1ToNRecursively(number,n,);
     }
 }
 
 void Print1ToNRecursively(int *number,int length,int index)
 {
     if(index==length-)
     {
         PrintNumber(number,length);
         return;
     }
     for(int i=;i<;i++)
     {
         number[index+]=i;
         Print1ToNRecursively(number,length,index+);
     }
 }
 
 void PrintNumber(int *number,int n)
 {
     int i=-;
     while(i<n&&number[++i]==) continue;
     while(i<n) cout<<number[i++];
     cout<<endl;
 }
 
 int main()
 {
     int n;
     while(cin>>n)
     {
         Print1ToN(n);
     }
     return ;
 }