# 2729. Check if The Number is Fascinating

## 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

• 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;
}
}

• 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";
}
};

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


• 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
}

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


• 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
}
}