打印1到最大的n位数

#include <iostream>
#include <string>
using namespace std;

// 参考《剑指offer》P94

bool increment_number(char *number){
  int take_over = 0;
  int len = strlen(number);
  for (int i = len - 1; i >= 0; --i){
    int sum = number[i] - '0' + take_over;

    // 最后一位加一
    if(i == len - 1){
      ++sum;
    }

    if(sum >= 10){
      sum -= 10;
      number[i] = '0' + sum;
      take_over = 1;

      // 进位到第0位，已经到达最大值
      if(i == 0)
        return true;
    }
    else {
      number[i] = '0' + sum;
      return false;
    }
  }

  return true;
}

void print_number(char *number){
  int len = strlen(number);
  bool flag = true;
  for (int i = 0; i < len; ++i){
    if (flag){
      if (number[i] == '0')
        continue;
      flag = false;
    }
    cout << number[i];
  }
  cout << endl;
}

void print_1_to_max_of_n_digits_core1(char *number, int n, int index){
  if(index == n - 1){
    print_number(number);
    return;
  }

  for(int i = 0; i < 10; ++i){
    number[index + 1] = '0' + i;
    print_1_to_max_of_n_digits_core1(number, n, index + 1);
  }
}

void print_1_to_max_of_n_digits_core2(char *number, int n, int index){
  for(int i = 0; i < 10; ++i){
    number[index] = '0' + i;

    if(index == n - 1){
      print_number(number);
      continue;
    }

    print_1_to_max_of_n_digits_core2(number, n, index + 1);
  }
}

void print_1_to_max_of_n_digits(int n){
  if(n <= 0)
    return;

  char *number = new char[n + 1];
  memset(number, '0', n);
  number[n] = '\0';

  // 大数加法解法
  //while(!increment_number(number))
  //  print_number(number);

  // 全排列解法1
  //for(int i = 0; i < 10; ++i){
  //  number[0] = '0' + i;
  //  print_1_to_max_of_n_digits_core1(number, n, 0);
  //}

  // 全排列解法2
  print_1_to_max_of_n_digits_core2(number, n, 0);

  delete [] number;
}

int main(){
  print_1_to_max_of_n_digits(2);

  int ttt = 0;
  return 0;
}