_179_LargestNumber.java

package leetcode_1To300;

import java.util.Arrays;
import java.util.Comparator;

/**
 * 本代码来自 Cspiration，由 @Cspiration 提供
 * 题目来源：http://leetcode.com
 * - Cspiration 致力于在 CS 领域内帮助中国人找到工作，让更多海外国人受益
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 * - 算法基础知识（上）（下）两部；题型技巧讲解（上）（下）两部
 * - 节省刷题时间，效率提高2-3倍，初学者轻松一天10题，入门者轻松一天20题
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 * - 版权所有，转发请注明出处
 */
public class _179_LargestNumber {
    /**
     * 179. Largest Number
     * 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.

     time : O(nlogn)
     space : O(n)

     * @param nums
     * @return
     */
    public String largestNumber(int[] nums) {
        if (nums == null || nums.length == 0) {
            return "";
        }
        String[] res = new String[nums.length];
        for (int i = 0; i < nums.length; i++) {
            res[i] = String.valueOf(nums[i]);
        }
        Arrays.sort(res, new Comparator<String>(){
            @Override
            public int compare(String str1, String str2) {
                String s1 = str1 + str2;
                String s2 = str2 + str1;
                return s2.compareTo(s1);
            }
        });
        if (res[0].charAt(0) == '0') {
            return "0";
        }
        StringBuilder sb = new StringBuilder();
        for (String s : res) {
            sb.append(s);
        }
        return sb.toString();
    }
}