Largest number formed from an array

//#include <iostream>
#include<bits/stdc++.h>
using namespace std;

bool comparator(string first,string second)
{
    string one = first+second;
    string two = second+first;
    
    int i=0;
    while(one[i] && two[i])
    {
        if(one[i]>two[i])
            return true;
        else if(one[i]<two[i])
            return false;
        ++i;
    }
    
    return false;
}

int main() {
	//code
	int tc;
	cin>>tc;
	while(tc--)
	{
	   int len;
	   vector<string> arr;
	   
	   //Take Array inputs
	   int i;
	   string temp;
	   cin>>len;
	   for(i=0;i<len;++i)
	   {
	       cin>>temp;
	       arr.push_back(temp);
	   }
	   
	   sort(arr.begin(),arr.end(),comparator);
	    
	   for(i=0;i<len;++i)
	       cout<<arr[i]<<" ";
	   cout<<"\n";
	}
	return 0;
}

def largestnumber(A):
extra=[]
l=len(str(max(A)))+1
for i in A:
tp=str(i)*l
extra.append((tp[:l:1],i))
extra.sort(reverse=True)
res=''
for i in extra:
res+=str(i[1])
return res

class Solution {
public String largestNumber(int[] nums) {

    List<String> list = new ArrayList<String>();
    
    for(int i=0;i<nums.length;i++){
        
        list.add(String.valueOf(nums[i]));
    }
    
    Collections.sort(list,new Comparator<>(){
       
        public int compare(String A,String B){
            
            
            String AB = A+B;
            String BA = B+A;
            
            return AB.compareTo(BA) > 0 ? -1 : 1;
        }
        
    });
    
    String res = "";
     for(int i=0;i<list.size();i++){
         res += list.get(i);
    }
    
    if(res.charAt(0) == '0')
        return "0";
    
    return res;
}

}

String printLargest(String[] arr) {

  StringBuilder stringBuilder = new StringBuilder();

    Arrays.sort(arr, (String a, String b) -> {
        String ab=a+b;
        String ba=b+a;
        return ab.compareTo(ba) > 0 ? -1 :1;
    });

    for(int i=0;i<arr.length;i++){
        stringBuilder.append(arr[i]);
    }
    if (stringBuilder.length()==0){
        return "0";
    }
    return stringBuilder.toString();
}

If someone came here looking for Javascript implementation

function sortArray(arr){
    arr.sort(function compare(first,second) {
        var firstsecond ='' + first + second;
        var secondfirst ='' + second + first;
        return firstsecond>secondfirst ? -1:1;
    })
}

function getLargestNumber(arr){
    var largestNumber = arr.join('')
    return largestNumber
}
var arr = [13,2,4]
sortArray(arr)
var result = getLargestNumber(arr)
console.log(result)

In Python This will also be the easiest Solution ::

a=[x for x in input().split()] #Taking Input in List
for i in range(len(a)):
for j in range(i+1,len(a)):
str1=a[i]+a[j]
str2=a[j]+a[i]
if int(str1)>int(str2):
pass
else:
a[i],a[j]=a[j],a[i]
for i in a:
print(i,end='')

OUTPUT ::

Pls attach Python code

def check(nums):
maximum=str(max(nums))
new_l=len(maximum)2
l=[]
for i in nums:
value=str(i)(new_l//len(str(i)))
l.append((value,str(i)))
res=''
for k in sorted(l,reverse=True):
res+=k[1]
result=int(res)
return str(result)

#python code
def largestnumber(a):
largestnumber =''
for i in range(len(a)-1):
for j in range(i+1, len(a)):
temp1 = str(a[i])+str(a[j])
temp2 = str(a[j])+str(a[i])
if int(temp2) > int(temp1):
a[i] , a[j] = a[j] , a[i]
for i in range(len(a)):
largestnumber += str(a[i])
return int(largestnumber)

print(largestnumber([3,30,34,9])

i login to give you a thumbup!

Pls attach Python code

from functools import cmp_to_key
class Solution:
    def largestNumber(self, nums: List[int]) -> str:
        def comp(x,y):
            if int(str(x)+str(y))>int(str(y)+str(x)):
                return -1
            else:
                return 1
               
        nums.sort(key=cmp_to_key(comp))
    
        ans=""
        for i in nums:
            ans+=str(i)
        if ans[0]=='0':
            return "0"
        return ans

please provide python code for nlogn without importing the permutations

please attach javascript code

@Bhargav1224 here it is in the comment above :) https://gist.github.com/SuryaPratapK/e7211a71677eb30933ae9c22fda6bb55?permalink_comment_id=3650870#gistcomment-3650870

Pls attach Python code

from itertools import permutations def largest(l): lst = [] for i in permutations(l, len(l)): # provides all permutations of the list values, # store them in list to find max lst.append("".join(map(str,i))) return max(lst)

print(largest([54, 546, 548, 60])) #Output 6054854654

from itertools import permutations


def permutation_method(l):
    lst = []
    for i in permutations(l):
        lst.append("".join(map(str, i)))
    return max(lst)


def normal_method(l):
    for i in range(len(l)):
        for j in range(i+1, len(l)):
            temp1 = int(str(l[i]) + str(l[j]))
            temp2 = int(str(l[j]) + str(l[i]))
            if temp1 < temp2:
                l[i], l[j] = l[j], l[i]
    return "".join(str(i) for i in l)


# print(largest_2([54, 546, 548, 60]))  # Output 6054854654
# print(largest([54, 546, 548, 60]))  # Output 6054854654



import timeit, random
m = 1000000
testdata = [random.randrange(m + 1) for _ in range(6)]
assert permutation_method(testdata)
assert normal_method(testdata)
print(timeit.timeit("f(ab)", "from __main__ import permutation_method as f, testdata as ab", number=1000))
print(timeit.timeit("f(ab)", "from __main__ import normal_method as f, testdata as ab", number=1000))

#0.8338875
#0.01934020000000003

Using Permutation is taking more then 10 times time. Result is shown above

sheetalrm209/Programs@cdee004

public class HighNumber {

public static void main(String[] args) {
    int[] arr = { 3, 30, 8, 5, 2 };
    // Output = 853032
    int t = 0;
    for (int i = 0; i < arr.length; i++) {

        for (int j = i + 1; j < arr.length; j++) {

            String ij = String.valueOf(arr[i]) + String.valueOf(arr[j]);
            String ji = String.valueOf(arr[j]) + String.valueOf(arr[i]);

            // System.out.println("ij: " + ij);
            // System.out.println("ji: " + ji);
            if (Integer.parseInt(ji) > Integer.parseInt(ij)) {

                t = arr[i];
                arr[i] = arr[j];
                arr[j] = t;
            }

        }

    }

 
    for (int i = 0; i < arr.length; i++) {

        System.out.println(arr[i]);
    }
}

}

for simple technique

class Solution {
public:
string largestNumber(vector& nums) {
vectornums1;
string st="";
for(int i=0;i<nums.size();i++){
nums1.push_back(to_string(nums[i]));
}
for(int i=0;i<nums1.size();i++){
for(int j=i+1;j<nums1.size();j++){
if(nums1[i]+nums1[j]<nums1[j]+nums1[i])
swap(nums1[i],nums1[j]);
}
}
for(auto p:nums1){
st+=p;
}
return (st[0]=='0'?"0":st);
}
};