Submission #1983496

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
ll n, m, ans;

ll fact(ll x) {
    if (x == 0)
        return 1;
    return x * fact(x - 1) % ((int)1e9 + 7);
}

int main(void) {
    cin >> n >> m;
    if (abs(n-m) >= 2)
        ans = 0;
    else if (abs(n-m) == 1)
        ans = fact(n) * fact(m);
    else if (abs(n-m) == 0)
        ans = 2 * fact(n) * fact(m);

    ans = ans % ((int)1e9+7);
    cout << ans << endl;
    return 0;
}

Submission Info

Judge Result