Maximum number

... by Bittle in Programming Help October 27, 2018


Given an array of numbers, arrange them in a way that yields the largest value. For example, if the given numbers are {154, 546, 548, 60}, the arrangement 6054854654 gives the largest value.

Input: First line contains an integer N , Next line contains N integers separated by space.

Output: Print the maximum number that can be obtained by using given numbers.

Constraints: 1<=N<=1000000


First you need to have the numbers stored in an array of integers, then you do the following:

private static String largestNumber(int[] nums) {
    String[] strings = new String[nums.length];
    // convert the integer array into a string array
    for (int i = 0; i < nums.length; i++) {
        strings[i] = String.valueOf(nums[i]);
    // sort the string array by comparing values a and b
    // for example: "9" + "8" vs "8"+ "9", "98" > "89" so "98" goes first
    Arrays.sort(strings, (a, b) -> (b + a).compareTo(a + b));
    // combine the array into a big string
    StringBuilder sb = new StringBuilder();
    for (String s : strings) {
    // remove any leading zeros
    while (sb.charAt(0) == '0' && sb.length() > 1)
    // return the final value as a string, since it can be large and cause overflow
    return sb.toString();

-- EDIT --

It seems that the java solution was a bit confusing with the lambda expression, so I will do the same logic, but in C++

int compareStrings(string a, string b)
    // first append b to the end of a
    string ab = a.append(b);

    // then append a to the end of b
    string ba = b.append(a);

    // Now check which merge is bigger
    if( > 0){
        return 1;
    return 0;

void printLargest(vector<string> arr)
    // sort from beginning to end using the compareString method.
    // if any doubt, look at the online documentation for
    // method specifications
    sort(arr.begin(), arr.end(), compareStrings);

    // now that the array is sorted, just print out
    for (int i=0; i < arr.size() ; i++ )
        cout << arr[i];

Just call printLargest with a list of strings, such as

vector<string> arr;

//output should be 6054854654

Comment if you need anything else!

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