# Check if frequency of each digit is less than the digit

Given an integer n, the task is to check if frequency of each digit of the number is less than or equal to digit itself.

Examples:

```Input : 51241
Output : False

Input : 1425243
Output : True
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Naive Approach: Start from 0 and count the frequency for every digit upto 9, if at any place frequency is more than the digit value then return false, else return true.

## C++

 `// A C++ program to validate a number ` `#include ` `using` `namespace` `std; ` ` `  `// Function to validate number (Check if ` `// frequency of a digit is less than the ` `// digit itself or not) ` `bool` `validate(``long` `long` `int` `n) ` `{ ` `    ``for` `(``int` `i=0; i<10; i++) ` `    ``{ ` `        ``long` `long` `int` `temp = n;  ` `        ``int` `count = 0; ` `        ``while` `(temp) ` `        ``{ ` `            ``// If current digit of temp is ` `            ``// same as i ` `            ``if` `(temp % 10 == i) ` `                ``count++; ` ` `  `            ``// if frequency is greater than  ` `            ``// digit value, return false ` `            ``if` `(count > i) ` `                ``return` `false``; ` ` `  `            ``temp /= 10; ` `        ``} ` `    ``} ` `    ``return` `true``; ` `} ` ` `  `// driver program ` `int` `main() ` `{ ` `    ``long` `long` `int` `n = 1552793; ` `    ``if` `(validate(n)) ` `        ``cout << ``"True"``; ` `    ``else` `        ``cout << ``"False"``; ` `    ``return` `0; ` `}  `

## Java

 `// Java program to validate a number ` `import` `java .io.*; ` ` `  `public` `class` `GFG { ` ` `  `// Function to validate number (Check if ` `// frequency of a digit is less than the ` `// digit itself or not) ` `static` `boolean` `validate(``long` `n) ` `{ ` `    ``for` `(``int` `i = ``0``; i < ``10``; i++) ` `    ``{ ` `        ``long` `temp = n;  ` `        ``int` `count = ``0``; ` `        ``while` `(temp > ``0``) ` `        ``{ ` `            ``// If current digit of  ` `            ``// temp is same as i ` `            ``if` `(temp % ``10` `== i) ` `                ``count++; ` ` `  `            ``// if frequency is greater than  ` `            ``// digit value, return false ` `            ``if` `(count > i) ` `                ``return` `false``; ` ` `  `            ``temp /= ``10``; ` `        ``} ` `    ``} ` `    ``return` `true``; ` `} ` ` `  `    ``// Driver Code ` `    ``static` `public` `void` `main (String[] args) ` `    ``{ ` `            ``long` `n = ``1552793``; ` `        ``if` `(validate(n)) ` `            ``System.out.println(``"True"``); ` `        ``else` `            ``System.out.println(``"False"``); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## Python3

 `# Python3 program to validate a number ` ` `  `# Function to validate number (Check if  ` `# frequency of a digit is less than the ` `# digit itself or not) ` `def` `validate(n): ` ` `  `    ``for` `i ``in` `range``(``10``): ` `        ``temp ``=` `n;  ` `        ``count ``=` `0``; ` `        ``while` `(temp): ` `             `  `            ``# If current digit of temp is  ` `            ``# same as i ` `            ``if` `(temp ``%` `10` `=``=` `i): ` `                ``count``+``=``1``; ` ` `  `            ``# if frequency is greater than  ` `            ``# digit value, return false ` `            ``if` `(count > i): ` `                ``return` `-``1``; ` ` `  `            ``temp ``/``/``=` `10``; ` ` `  `    ``return` `1``; ` ` `  `# Driver Code ` `n ``=` `1552793``; ` `geek ``=` `"True"` `if` `validate(n) ``else` `"False"``; ` `print``(geek); ` ` `  `# This code is contributed by mits `

## C#

 `// C# program to validate a number ` `using` `System; ` ` `  `public` `class` `GFG { ` ` `  `// Function to validate number (Check if ` `// frequency of a digit is less than the ` `// digit itself or not) ` `static` `bool` `validate(``long` `n) ` `{ ` `    ``for` `(``int` `i = 0; i < 10; i++) ` `    ``{ ` `        ``long` `temp = n;  ` `        ``int` `count = 0; ` `        ``while` `(temp > 0) ` `        ``{ ` `            ``// If current digit of  ` `            ``// temp is same as i ` `            ``if` `(temp % 10 == i) ` `                ``count++; ` ` `  `            ``// if frequency is greater than  ` `            ``// digit value, return false ` `            ``if` `(count > i) ` `                ``return` `false``; ` ` `  `            ``temp /= 10; ` `        ``} ` `    ``} ` `    ``return` `true``; ` `} ` ` `  `    ``// Driver Code ` `    ``static` `public` `void` `Main(String[] args) ` `    ``{ ` `            ``long` `n = 1552793; ` `        ``if` `(validate(n)) ` `            ``Console.WriteLine(``"True"``); ` `        ``else` `            ``Console.WriteLine(``"False"``); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## PHP

 ` ``\$i``) ` `                ``return` `-1; ` ` `  `            ``\$temp` `/= 10; ` `        ``} ` `    ``} ` `    ``return` `1; ` `} ` ` `  `    ``// Driver Code ` `    ``\$n` `= 1552793; ` `    ``\$geek` `= validate(``\$n``) ?``"True"` `:``"False"``; ` `    ``echo``(``\$geek``); ` ` `  `// This code is contributed by Ajit ` `?> `

Output:

```True
```

Efficient Approach: is to store the frequency of each digit and if at any place frequency is more than the digit value then return false, else return true.

## C++

 `// A C++ program to validate a number ` `#include ` `using` `namespace` `std; ` ` `  `// Function to validate number (Check if  ` `// frequency of a digit is less than the  ` `// digit itself or not) ` `bool` `validate(``long` `long` `int` `n) ` `{ ` `    ``int` `count = {0};   ` `    ``while` `(n) ` `    ``{ ` `        ``// calculate frequency of each digit ` `        ``int` `r = n % 10; ` ` `  `        ``// If count is already r, then ` `        ``// incrementing it would invalidate,  ` `        ``// hence we return false. ` `        ``if` `(count[r] == r) ` `           ``return` `false``;   ` ` `  `        ``count[r]++; ` `        ``n /= 10; ` `    ``} ` ` `  `    ``return` `true``; ` `} ` ` `  `// driver program ` `int` `main() ` `{ ` `    ``long` `long` `int` `n = 1552793; ` `    ``if` `(validate(n)) ` `        ``cout << ``"True"``; ` `    ``else` `        ``cout << ``"False"``; ` `    ``return` `0; ` `}  `

## Java

 `// A Java program to ` `// validate a number ` `import` `java.io.*; ` ` `  `class` `GFG  ` `{ ` `     `  `// Function to validate ` `// number (Check if frequency  ` `// of a digit is less than  ` `// the digit itself or not) ` `static` `boolean` `validate(``long` `n) ` `{ ` `    ``int` `count[] = ``new` `int``[``10``] ;  ` `    ``while` `(n > ``0``) ` `    ``{ ` `        ``// calculate frequency  ` `        ``// of each digit ` `        ``int` `r = (``int``)n % ``10``; ` ` `  `        ``// If count is already r,  ` `        ``// then incrementing it  ` `        ``// would invalidate,  ` `        ``// hence we return false. ` `        ``if` `(count[r] == r) ` `        ``return` `false``;  ` ` `  `        ``count[r]++; ` `        ``n /= ``10``; ` `    ``} ` ` `  `    ``return` `true``; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `main (String[] args) ` `{ ` `    ``long` `n = ``1552793``; ` `    ``if` `(validate(n)) ` `        ``System.out.println(``"True"``); ` `    ``else` `        ``System.out.println(``"False"``); ` `} ` `} ` ` `  `// This code is contributed by ajit `

## Python3

 `# A Python3 program to validate a number ` `import` `math as mt ` ` `  `# Function to validate number (Check if  ` `# frequency of a digit is less than the  ` `# digit itself or not) ` `def` `validate(n): ` ` `  `    ``count ``=` `[``0` `for` `i ``in` `range``(``10``)]  ` `    ``while` `(n > ``0``): ` `     `  `        ``# calculate frequency of each digit ` `        ``r ``=` `n ``%` `10` ` `  `        ``# If count is already r, then ` `        ``# incrementing it would invalidate,  ` `        ``# hence we return false. ` `        ``if` `(count[r] ``=``=` `r): ` `            ``return` `False` ` `  `        ``count[r] ``+``=` `1` `        ``n ``=` `n ``/``/` `10` `     `  `    ``return` `True` ` `  `# Driver Code ` `n ``=` `1552793` `if` `(validate(n)): ` `    ``print``(``"True"``) ` `else``: ` `    ``print``(``"False"``) ` ` `  `# This code is contributed by  ` `# Mohit kumar 29 `

## C#

 `// A C# program to validate a number  ` `using` `System; ` ` `  `class` `GFG ` `{ ` `// Function to validate number  ` `// (Check if frequency of a digit is  ` `// less than the digit itself or not)  ` `static` `bool` `validate(``long` `n)  ` `{  ` `    ``int` `[]count = ``new` `int`` ;  ` `    ``while` `(n > 0)  ` `    ``{  ` `        ``// calculate frequency  ` `        ``// of each digit  ` `        ``int` `r = (``int``)n % 10;  ` ` `  `        ``// If count is already r, then   ` `        ``// incrementing it would invalidate,  ` `        ``// hence we return false.  ` `        ``if` `(count[r] == r)  ` `        ``return` `false``;  ` ` `  `        ``count[r]++;  ` `        ``n /= 10;  ` `    ``}  ` ` `  `    ``return` `true``;  ` `}  ` ` `  `// Driver Code  ` `static` `public` `void` `Main () ` `{ ` `    ``long` `n = 1552793;  ` `    ``if` `(validate(n))  ` `        ``Console.WriteLine(``"True"``);  ` `    ``else` `        ``Console.WriteLine(``"False"``);  ` `}  ` `}  ` ` `  `// This code is contributed by jit_t `

## PHP

 ` `

Output:

```True
```

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