public static long nCr ( int n , int r ) {
  long M = 1000000007L ;
  long dp [ ] [ ] = new long [ 502 ] [ 502 ] ;
  for ( int i = 0 ;
  i < 502 ;
  ++ i ) {
    for ( int j = 0 ;
    j < 502 ;
    ++ j ) {
      dp [ i ] [ j ] = 0 ;
    }
  }
  dp [ 0 ] [ 0 ] = 1 ;
  for ( int i = 1 ;
  i <= n ;
  ++ i ) {
    dp [ i ] [ 0 ] = 1 ;
    for ( int j = 1 ;
    j <= i + 1 ;
    ++ j ) {
      dp [ i ] [ j ] = ( dp [ i - 1 ] [ j - 1 ] + dp [ i - 1 ] [ j ] ) % M ;
    }
  }
  return dp [ n ] [ r ] ;
}

public static long nCr ( int n , int r ) { long M = 1000000007L ; long dp [ ] [ ] = new long [ 502 ] [ 502 ] ; for ( int i = 0 ; i < 502 ; ++ i ) { for ( int j = 0 ; j < 502 ; ++ j ) { dp [ i ] [ j ] = 0 ; } } dp [ 0 ] [ 0 ] = 1 ; for ( int i = 1 ; i <= n ; ++ i ) { dp [ i ] [ 0 ] = 1 ; for ( int j = 1 ; j <= i + 1 ; ++ j ) { dp [ i ] [ j ] = ( dp [ i - 1 ] [ j - 1 ] + dp [ i - 1 ] [ j ] ) % M ; } } return dp [ n ] [ r ] ; }
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