LeetCode 2729. Check if The Number is Fascinating Solution in Java, C++, Python & More | Explanation + Code

Description

You are given an integer n that consists of exactly 3 digits.

We call the number n fascinating if, after the following modification, the resulting number contains all the digits from 1 to 9 exactly once and does not contain any 0's:

• Concatenate n with the numbers 2 * n and 3 * n.

Return true if n is fascinating, or false otherwise.

Concatenating two numbers means joining them together. For example, the concatenation of 121 and 371 is 121371.

 

Example 1:

Input: n = 192
Output: true
Explanation: We concatenate the numbers n = 192 and 2 * n = 384 and 3 * n = 576. The resulting number is 192384576. This number contains all the digits from 1 to 9 exactly once.

Example 2:

Input: n = 100
Output: false
Explanation: We concatenate the numbers n = 100 and 2 * n = 200 and 3 * n = 300. The resulting number is 100200300. This number does not satisfy any of the conditions.

 

Constraints:

• 100 <= n <= 999

Solutions

Solution 1

PythonJavaC++GoTypeScriptRust

class Solution: def isFascinating(self, n: int) -> bool: s = str(n) + str(2 * n) + str(3 * n) return "".join(sorted(s)) == "123456789"(code-box)

class Solution { public boolean isFascinating(int n) { String s = "" + n + (2 * n) + (3 * n); int[] cnt = new int[10]; for (char c : s.toCharArray()) { if (++cnt[c - '0'] > 1) { return false; } } return cnt[0] == 0 && s.length() == 9; } }(code-box)

class Solution { public: bool isFascinating(int n) { string s = to_string(n) + to_string(n * 2) + to_string(n * 3); sort(s.begin(), s.end()); return s == "123456789"; } };(code-box)

func isFascinating(n int) bool { s := strconv.Itoa(n) + strconv.Itoa(n*2) + strconv.Itoa(n*3) cnt := [10]int{} for _, c := range s { cnt[c-'0']++ if cnt[c-'0'] > 1 { return false } } return cnt[0] == 0 && len(s) == 9 }(code-box)

function isFascinating(n: number): boolean { const s = `${n}${n * 2}${n * 3}`; return s.split('').sort().join('') === '123456789'; }(code-box)

impl Solution { pub fn is_fascinating(n: i32) -> bool { let s = format!("{}{}{}", n, n * 2, n * 3); let mut cnt = vec![0; 10]; for c in s.chars() { let t = (c as usize) - ('0' as usize); cnt[t] += 1; if cnt[t] > 1 { return false; } } cnt[0] == 0 && s.len() == 9 } }(code-box)

Solution 2

Rust

use std::collections::HashMap; impl Solution { pub fn is_fascinating(mut n: i32) -> bool { let mut i = n * 2; let mut j = n * 3; let mut hash = HashMap::new(); while n != 0 { let cnt = hash.entry(n % 10).or_insert(0); *cnt += 1; n /= 10; } while i != 0 { let cnt = hash.entry(i % 10).or_insert(0); *cnt += 1; i /= 10; } while j != 0 { let cnt = hash.entry(j % 10).or_insert(0); *cnt += 1; j /= 10; } for k in 1..=9 { if !hash.contains_key(&k) || hash[&k] > 1 { return false; } } !hash.contains_key(&0) } }(code-box)