N！ (数组）

#include <iostream>
using namespace std;
const int MAXN = 3000;
int f[MAXN];

int main(){
    int n;
    cin >> n;
    f[0] = 1;
    int i, j;
    for(i = 2; i <= n; i++){
        int c = 0;
        for(j = 0; j < MAXN; j++){
            int s = f[j] * i + c;
            c = s / 10;
            f[j] = s % 10;
        }
    }
    for(j = MAXN - 1; j >= 0; j--){
        if(f[j]) break;
    }
    for(i = j; i >= 0; i--)
        cout << f[i];
    cout << endl;
    return 0;
}