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

Example 1:

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Input: [10,2]
Output: "210"

Example 2:

Input: [3,30,34,5,9]
Output: "9534330"

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

 

class Solution {
    private class LargerNumberComparator implements Comparator<String> {
        @Override
        public int compare(String a, String b) {
            String order1 = a + b;
            String order2 = b + a;
           return order2.compareTo(order1);
        }
    }

    public String largestNumber(int[] nums) {
        // Get input integers as strings.
        String[] asStrs = new String[nums.length];
        for (int i = 0; i < nums.length; i++) {
            asStrs[i] = String.valueOf(nums[i]);
        }

        // Sort strings according to custom comparator.
        Arrays.sort(asStrs, new LargerNumberComparator());

        // If, after being sorted, the largest number is `0`, the entire number
        // is zero.
        if (asStrs[0].equals("0")) {
            return "0";
        }

        // Build largest number from sorted array.
        String largestNumberStr = new String();
        for (String numAsStr : asStrs) {
            largestNumberStr += numAsStr;
        }

        return largestNumberStr;
    }
}

重写comparator interface 里面的compare方法，然后使用method Arrays.sort(array[], new Comparator<String>());

sort完了就是降序排列。

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