一个自描述数字是整数n，在给定的底数b内是b位数字，其中位置p处的每个数字(最高有效位在位置0处，最低有效位在位置b-1处)计算一个数字p的次数。在n中。
例如，在以10为底的数字中， 6210001000是一个自描述数字。
解释 ：
以10为基数的10位数字。
它在位置0处有6，在6210001000中有六个0。
它在位置1有2，在6210001000中有两个1。
它在位置2有1，而在6210001000中有2。
它在位置3处为0，在6210001000中为零3s。
它在位置4处为0，而在6210001000中为零4s。
它在位置5处为0，而在6210001000中为零5s。
它在位置6有1，在6210001000中有一个6。
它在位置7处为0，而在6210001000中为零7s。
它在位置8处为0，在6210001000中为零8s。
它在位置9处为0，而在6210001000中为零。
[资料来源：维基百科]
Here is a program to print all self-descriptive numbers below 100000000. In the below program we have just ignored one fact about the self-descriptive number that it should have as many number of digits as much the base is given.
程序说明：
1。首先，所有数字都从外循环中提取出来，并在每次迭代中存储在变量b中。
2。然后在内部循环中，对字符串存在i次数(这是外部循环的第i个索引)进行计数。
3。最后，将该计数与存储在变量b中的第i个索引处的数字进行比较。
C++
// C++ program to print
// all self descriptive
// number below 100000000
#include
using namespace std;
bool isSelfDescriptiveNumber(int num)
{
// converting the integer
// num to string
string s = to_string(num);
for (int i = 0;
i < s.size(); i++)
{
// Extracting each digit
// one by one from the
// string
char temp_char = s.at(i);
// converting the string
// (digit) into integer b
// variable stores the digit
// present at index 'i'
int b = temp_char - '0';
// counting how many
// times the particular
// digit occur in the
// whole number "num"
int count = 0;
for (int j = 0;
j < s.size(); j++)
{
// converting string
// char to integer
int temp = s.at(j) - '0';
// checking whether it is
// equal to the index 'i'
// if it is then increment
// the count .
if (temp == i)
{
count++;
}
}
// If it is not equal
// it return false .
if (count != b)
return false;
}
return true;
}
// Driver Code
int main()
{
for (int i = 0; i < 100000000; i++)
if (isSelfDescriptiveNumber(i))
cout << i << endl;
}
// This code is contributed by
// Manish Shaw(manishshaw1) Java
// Java program to print all self descriptive
// number below 100000000
public class SelfDescriptive {
public static boolean isSelfDescriptiveNumber(int num)
{
// converting the integer num to string
String s = Integer.toString(num);
for (int i = 0; i < s.length(); i++) {
// Extracting each digit one by one from the string
String temp_char = s.charAt(i) + "";
// converting the string (digit) into integer
// b variable stores the digit present at index 'i'
int b = Integer.parseInt(temp_char);
// counting how many times the particular digit
// occur in the whole number "num"
int count = 0;
for (int j = 0; j < s.length(); j++) {
// converting string char to integer
int temp = Integer.parseInt(s.charAt(j) + "");
// checking whether it is equal to the index 'i'
// if it is then increment the count .
if (temp == i) {
count++;
}
}
// If it is not equal
// it return false .
if (count != b)
return false;
}
return true;
}
public static void main(String[] args)
{
for (int i = 0; i < 100000000; i++)
if (isSelfDescriptiveNumber(i))
System.out.println(i);
}
}Python3
# Python3 program to print
# all self descriptive
# number below 100000000
def isSelfDescriptiveNumber(num):
# Converting the integer
# num to string
s = str(num)
for i in range(len(s)):
# Extracting each digit
# one by one from the
# string
temp_char = s[i]
# Converting the string
# (digit) into integer b
# variable stores the digit
# present at index 'i'
b = ord(temp_char) - ord('0')
# Counting how many
# times the particular
# digit occur in the
# whole number "num"
count = 0
for j in range(len(s)):
# Converting string
# char to integer
temp = ord(s[j]) - ord('0')
# Checking whether it is
# equal to the index 'i'
# if it is then increment
# the count .
if (temp == i):
count += 1
# If it is not equal
# it return false .
if (count != b):
return False
return True
# Driver code
if __name__=="__main__":
for i in range(100000000):
if (isSelfDescriptiveNumber(i)):
print(i)
# This code is contributed by rutvik_56C#
// C# program to print
// all self descriptive
// number below 100000000
using System;
class GFG
{
static bool isSelfDescriptiveNumber(int num)
{
// converting the integer
// num to string
string s = num.ToString();
for (int i = 0;
i < s.Length; i++)
{
// Extracting each digit
// one by one from the
// string
string temp_char = s[i] + "";
// converting the string
// (digit) into integer b
// variable stores the digit
// present at index 'i'
int b = int.Parse(temp_char);
// counting how many
// times the particular
// digit occur in the
// whole number "num"
int count = 0;
for (int j = 0;
j < s.Length; j++)
{
// converting string
// char to integer
int temp = int.Parse(s[j] + "");
// checking whether it is
// equal to the index 'i'
// if it is then increment
// the count .
if (temp == i)
{
count++;
}
}
// If it is not equal
// it return false .
if (count != b)
return false;
}
return true;
}
// Driver Code
static void Main()
{
for (int i = 0; i < 100000000; i++)
if (isSelfDescriptiveNumber(i))
Console.WriteLine(i);
}
}
// This code is contributed by
// Manish Shaw(manishshaw1)PHP
输出：
1210
2020
21200
3211000