[LeetCode 179] Largest Number

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;

/**
 * 
	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.
 *
 */

public class LargestNumber {

	
    //解法一
//  221 / 221 test cases passed.
//  Status: Accepted
//  Runtime: 250 ms
//  Submitted: 0 minutes ago
	//时间复杂度O(n ^ 2) 	空间复杂度O(n)
  public String  largestNumber(int[] num) {
      String largest = "";
  	List<String> num_str = new ArrayList<String>();
  	for (int i = 0; i < num.length; i++) {
			num_str.add(num[i] + "");
		}
  	//对数值字符串排序
  	num_str.sort(new Comparator<String>() {
  		public int compare(String s1, String s2) {
				String s1Adds2 = s1 + s2;
				String s2Adds1 = s2 + s1;
  			return s2Adds1.compareTo(s1Adds2);
  		}
  	});
  	//连接字符
  	for (int i = 0; i < num_str.size(); i++) {
  		largest += num_str.get(i);
		}
  	//消除前缀是000...00的情况
  	int beginIndex = 0;
  	while(beginIndex < largest.length() - 1 
  			&& largest.charAt(beginIndex) == '0') beginIndex ++;
  	
  	return largest.substring(beginIndex);
  }
  

	//解法二
//	221 / 221 test cases passed.
//	Status: Accepted
//	Runtime: 250 ms
//	Submitted: 0 minutes ago
	
	//时间复杂度O(n ^ 2) 	空间复杂度O(n)
    public String  largestNumber1(int[] num) {
        String largest = "";
    	List<String> num_str = new ArrayList<String>();
    	for (int i = 0; i < num.length; i++) {
			num_str.add(num[i] + "");
		}
    	//对数值字符串排序
    	num_str.sort(new Comparator<String>() {
    		public int compare(String s1, String s2) {
				int len1 = s1.length();
				int len2= s2.length();
    			if(len1 < len2) {
    				int n = len2 / len1;
					for (int i = 0; i < n * len1; i += len1) {
						if (!s2.substring( i, i + len1).equals(s1)) 
							return s2.substring(i, i + len1).compareTo(s1);
					}
					if (len2 % len1 != 0) 
						return	compare(s1, s2.substring(len2 - len2 % len1, len2));
    			} else if(len1 > len2){
    				int n = len1 / len2;
    				for (int i = 0; i < n * len2; i += len2) {
						if (!s1.substring(i, i + len2).equals(s2)) 
							return s2.compareTo(s1.substring(i, i + len2));
					}
					if (len1 % len2 != 0) 
						return compare(s1.substring(len1 - len1 % len2, len1), s2);
				}
    			return s2.compareTo(s1);
    		}
    	});
    	//连接字符
    	for (int i = 0; i < num_str.size(); i++) {
    		largest += num_str.get(i);
		}
    	//消除前缀是000...00的情况
    	int beginIndex = 0;
    	while(beginIndex < largest.length() - 1 
    			&& largest.charAt(beginIndex) == '0') beginIndex ++;
    	
    	return largest.substring(beginIndex);
    }

	public static void main(String[] args) {

	}

}