Submission #1381535

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Source Code Expand

#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <limits.h>
#include <map>
#include <algorithm>
#include <functional>
using namespace std;

long long func( int a, int b, long long  p ) {
    if ( b == 0 ) {
        return 1;
    }
    else if ( b%2 == 0 ) {
        long long temp = func( a, b/2, p );
        return (temp * temp)%p;
    }
    else {
        return ( func( a, b-1, p ) * a ) % p;
    }
    
}

int main() {
    
    int W,H;
    
    cin >> W;
    cin >> H;
    
    long long ans = 1;
    
    int s = min( W-1, H-1 );
    int l = max( W-1, H-1 );
    
    int a = l+s;
    
    while( a ) {
        ans *= a;
        ans %= 1000000007;
        a--;
    } 
    
    a = l;
    
    while ( a ) {
        ans *= func( a, 1000000005, 1000000007 );
        ans %= 1000000007;
        a--;
    }
    
    a = s;
    
    while ( a ) {
        ans *= func( a, 1000000005, 1000000007 );
        ans %= 1000000007;
        a--;
    }
    
    cout << ans << endl;
    
    return 0;
}

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