Submission #1858913

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Source Code Expand

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define fbo find_by_order
#define ook order_of_key

typedef long long ll;
typedef pair<ll,ll> ii;
typedef vector<int> vi;
typedef long double ld;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0);
    ll mod=1e9+7;
    ll n,m;
    cin>>n>>m;
    if(n<m)
        swap(n,m);
    ll ans=1;
    if(n-m>1){
        cout<<0;
    }
    else if(n-m==1){
        for(ll i=1;i<=n;i++){
            ans=ans*i;
            ans=ans%mod;
        }
        for(ll i=1;i<=m;i++){
            ans=ans*i;
            ans=ans%mod;
        }
        cout<<ans;
    }
    else if(n-m==0){
        ans=2;
        for(ll i=1;i<=n;i++){
            ans=ans*i;
            ans=ans%mod;
        }
        for(ll i=1;i<=m;i++){
            ans=ans*i;
            ans=ans%mod;
        }
        cout<<ans;
    }
}

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