LeetCode 2520. Count the Digits That Divide a Number Solution in Java, C++, Python & More | Explanation + Code

Description

Given an integer num, return the number of digits in num that divide num.

An integer val divides nums if nums % val == 0.

 

Example 1:

Input: num = 7
Output: 1
Explanation: 7 divides itself, hence the answer is 1.

Example 2:

Input: num = 121
Output: 2
Explanation: 121 is divisible by 1, but not 2. Since 1 occurs twice as a digit, we return 2.

Example 3:

Input: num = 1248
Output: 4
Explanation: 1248 is divisible by all of its digits, hence the answer is 4.

 

Constraints:

• 1 <= num <= 109
• num does not contain 0 as one of its digits.

Solutions

Solution 1: Enumeration

We directly enumerate each digit val of the integer num, and if val can divide num, we add one to the answer.

After the enumeration, we return the answer.

The time complexity is O(log num), and the space complexity is O(1).

PythonJavaC++GoTypeScriptRustC

class Solution: def countDigits(self, num: int) -> int: ans, x = 0, num while x: x, val = divmod(x, 10) ans += num % val == 0 return ans(code-box)

class Solution { public int countDigits(int num) { int ans = 0; for (int x = num; x > 0; x /= 10) { if (num % (x % 10) == 0) { ++ans; } } return ans; } }(code-box)

class Solution { public: int countDigits(int num) { int ans = 0; for (int x = num; x > 0; x /= 10) { if (num % (x % 10) == 0) { ++ans; } } return ans; } };(code-box)

func countDigits(num int) (ans int) { for x := num; x > 0; x /= 10 { if num%(x%10) == 0 { ans++ } } return }(code-box)

function countDigits(num: number): number { let ans = 0; for (let x = num; x; x = (x / 10) | 0) { if (num % (x % 10) === 0) { ++ans; } } return ans; }(code-box)

impl Solution { pub fn count_digits(num: i32) -> i32 { let mut ans = 0; let mut cur = num; while cur != 0 { if num % (cur % 10) == 0 { ans += 1; } cur /= 10; } ans } }(code-box)

int countDigits(int num) { int ans = 0; int cur = num; while (cur) { if (num % (cur % 10) == 0) { ans++; } cur /= 10; } return ans; }(code-box)

Solution 2

TypeScriptRust

function countDigits(num: number): number { let ans = 0; for (const s of num.toString()) { if (num % Number(s) === 0) { ans++; } } return ans; }(code-box)

impl Solution { pub fn count_digits(num: i32) -> i32 { num.to_string() .chars() .filter(|&c| c != '0') .filter(|&c| num % (c.to_digit(10).unwrap() as i32) == 0) .count() as i32 } }(code-box)