3848. Check Digitorial Permutation

You are given an integer n.

A number is called digitorial if the sum of the factorials of its digits is equal to the number itself.

Determine whether any permutation of n (including the original order) forms a digitorial number.

Return true if such a permutation exists, otherwise return false.

Note:

• The factorial of a non-negative integer x, denoted as x!, is the product of all positive integers less than or equal to x, and 0! = 1.
• A permutation is a rearrangement of all the digits of a number that does not start with zero. Any arrangement starting with zero is invalid.

class Solution {
public:
    bool isDigitorialPermutation(int n) {
        int fact[10]{0,};
        for(int i = 0; i < 10; i++) {
            fact[i] = 1;
            for(int j = 1; j <= i; j++) fact[i] *= j;
        }
        int sum = 0, x = n;
        while(x) {
            sum += fact[x%10];
            x /= 10;
        }
        unordered_map<int,int> freq;
        while(n) {
            freq[n%10]++; n/=10;
        }
        while(sum) {
            freq[sum%10]--; sum/= 10;
        }
        for(auto& [k,v] : freq) if(v) return false;
        return true;
    }
};