# 179 Largest Number – Medium

### Problem:

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given \[3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

### Thoughts:

The trick is to implement a custom comparator then leverage Arrays.sort method. Also, note that if implement Comparator, you cannot use Arrays.sort(int\[\[], CustomComparator) because int cannot be automatically casted into Integer object in this case.

### Solutions:

```java
public class Solution {
    public String largestNumber(int[] nums) {
        String[] snums = new String[nums.length];
        for (int i = 0; i < nums.length; i ++){
            snums[i] = "" + nums[i];
        } 
        Arrays.sort(snums, new Comparator<String>(){
            public int compare(String a, String b){
                String atob = a + b;
                String btoa = b + a;
                return btoa.compareTo(atob);
            }
        });
        String result = "";
        for (int i = 0; i < snums.length; i ++){ 
            result +=snums[i]; 
        } //remove front zeroes 
        while (result.length() > 1){
            if (result.charAt(0) == '0')
                result = result.substring(1);
            else
                break;
        }
        return result;
    }//largestNumber
}
```

```java
public class Solution {
    class StrComparator implements Comparator<String> {
        @Override
        public int compare(String s1, String s2) {
            String s1s2 = s1 + "" + s2;
            String s2s1 = s2 + "" + s1;
            return s1s2.compareTo(s2s1);
        }
    }
    public String largestNumber(int[] nums) {
        String[] strs = new String[nums.length];
        for (int i = 0; i < nums.length; i ++) {
            strs[i] = nums[i] + "";
        }
        Arrays.sort(strs, new StrComparator());
        String result = "";
        for (int i = 0; i < strs.length; i ++) {
            result = strs[i] + result;
        }
        if (result.charAt(0) == '0') {
            return "0";
        }
        return result;
    }
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ugopireddy.gitbook.io/leet-code-solutions/solutions_151_-_200/179-largest-number-medium.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.