1175. 质数排列

质数数阶乘乘以非质数阶乘

计算的过程中容易越界，可以考虑用long long存，返回时强制转换

class Solution {
public:
    const int MOD = 1e9+7; 
    int numPrimeArrangements(int n) {
        int primes[] = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101};
        int p = 0;
        while(primes[p] <= n) p++;
        int t = n - p;
        long long res = t;
        for(int i = 1; i < t; i++){
                res = res * i % MOD;
        } 
        for(int i = 1; i <= p; i++){
               res = res * i % MOD; 
        }
        return int(res);
    }
};