human
Smallest number greater than Y with sum of digits equal to X | Function to return the minimum string of length d having the sum of digits s.
Return a string of length d.
Greedily put 9 's  in the end.
Put remaining sum.
Function to find the smallest number greater than Y whose sum of digits is X.
Convert number y to string.
Maintain prefix sum of digits.
Iterate over Y from the back where k is current length of suffix.
Stores current digit.
Increase current digit.
Sum upto current prefix.
Return answer if remaining sum can be obtained in suffix.
Find suffix of length k having sum of digits x - r.
Append current character.
Return the result.
Driver Code.
Given Number and Sum.
Function Call"
Solution in Python:

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What is a code to smallest number greater than Y with sum of digits equal to X and the other steps required?
assistant
#Here is code to smallest number greater than Y with sum of digits equal to X and the other steps required.
 def helper ( d , s ) :
	ans = [ '0' ] * d
	for i in range ( d - 1 , - 1 , - 1 ) :
		if ( s >= 9 ) :
			ans [ i ] = '9'
			s -= 9
		else :
			c = chr ( s + ord ( '0' ) )
			ans [ i ] = c ;
			s = 0 ;
	return ' ' . join ( ans ) ;
def findMin ( x , Y ) :
	y = str ( Y ) ;
	n = len ( y )
	p = [ 0 ] * n
	for i in range ( n ) :
		p [ i ] = ( ord ( y [ i ] ) - ord ( '0' ) )
		if ( i > 0 ) :
			p [ i ] += p [ i - 1 ] ;
	n - 1
	k = 0
	while True :
		d = 0 ;
		if ( i >= 0 ) :
			d = ( ord ( y [ i ] ) - ord ( '0' ) )
		for j in range ( d + 1 , 10 ) :
			r = ( ( i > 0 ) * p [ i - 1 ] + j ) ;
			if ( x - r >= 0 and x - r <= 9 * k ) :
				suf = helper ( k , x - r ) ;
				pre = " " ;
				if ( i > 0 ) :
					pre = y [ 0 : i ]
				cur = chr ( j + ord ( '0' ) )
				pre += cur ;
				return pre + suf ;
		i -= 1
		k += 1
if __name__ == " _ _ main _ _ " :
	x = 18 ;
	y = 99 ;
	print ( findMin ( x , y ) )