# 算法：如何排列给定数字以形成最大数？|S2

## 本文概述

``````Input :  [1, 34, 3, 98, 9, 76, 45, 4, 12, 121]
Output : 99876454343121211

Input :  [12, 121]
Output : 12121``````

In设置1, 我们已经讨论了执行此操作的方法。在这一组中, 我们将讨论另一种逻辑。

1)找出最大位数的位数。令数字为n。

2)创建所有数字的扩展版本。在扩展版本中, 我们将n的数字与其自身连接起来并截断多余的数字, 从而形成n + 1个数字。

3)根据原始数字的扩展值对它们进行排序。

4)连接排序的数字将产生所需的结果。

## Java

``````// Java program to arrange the numbers to form the
// largest number
import java.math.BigInteger;
import java.util.*;

public class LargestNumber
{
// method that returns largest number form
public static String largestNumber(List<Integer> arr)
{
// finding number of digits in maximum element
// present in array
int n =
Collections.max(arr).toString().length();

ArrayList<ExtendedNum> en =
new ArrayList<ExtendedNum>();
for ( int i = 0 ; i < arr.size(); i++)
en.add( new ExtendedNum(arr.get(i), n));

// sort based on modified value
Collections.sort(en, (p1, p2) ->
( int )(p2.modifiedValue - p1.modifiedValue));

StringBuilder sb = new StringBuilder();
for ( int i = 0 ; i < en.size(); i++)
sb.append( new StringBuilder
(Long.toString(en.get(i).originalValue)));

// To remove any zeroes at head.
BigInteger bi = new BigInteger(sb.toString());

return bi.toString();
}

// Driver method
public static void main(String[] args)
{
Integer arr[] = { 1 , 34 , 3 , 98 , 9 , 76 , 45 , 4 , 12 , 121 };
List<Integer> l = Arrays.asList(arr);

System.out.println(largestNumber(l));
}
}

// A utility class to generate new value
class ExtendedNum
{
int originalValue;
long modifiedValue;

public ExtendedNum( int originalValue, int n)
{
this .originalValue = originalValue;
String s = Integer.toString(originalValue);
StringBuilder sb = new StringBuilder(s);
StringBuilder ans = new StringBuilder();
while (ans.length() <= n + 1 )
ans.append(sb);

s = ans.toString().substring( 0 , n + 1 );
modifiedValue = Long.parseLong(s);
}

public String toString()
{
return "[" + modifiedValue +
", " + originalValue + "]" ;
}
}``````

## python

``````# Python program to find largest
# number from the given values
# function that return largest
# possible number
def largestNumber(array):

# extval is a empty list for extended
# values and ans for calculating answer
extval, ans = [], ""

# calculating the length of largest number
# from given and add 1 for further operation
l = len ( str ( max (array))) + 1

# iterate given values and
# calculating extended values
for i in array:
temp = str (i) * l

# make tuple of extended value and
# equivalant original value then
# append to list
extval.append((temp[:l:], i))

# sort extval in descending order
extval.sort(reverse = True )

# iterate extended values
for i in extval:

# concatinate original value equivalant
# to extended value into ans variable
ans + = str (i[ 1 ])

if int (ans) = = 0 :
return "0"
return ans

# Driver code
a = [ 1 , 34 , 3 , 98 , 9 , 76 , 45 , 4 , 12 , 121 ]

print (largestNumber(a))

# This code is contributed by Chhekur``````

``99876454343121211``

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