Largest Number

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本文探讨了如何通过定义特殊的字符串排序标准来解决将整数转换为字符串并排列成最大数值的问题，特别关注于大数值的处理，确保最终结果以字符串形式返回。

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.

解题思路：首先将Int转化为字符串，定义一个字符串的排序标准进行排序；

#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<sstream>
using namespace std;
bool CompareString(const string &s1,const string &s2)
{
	return (s1 + s2) > (s2 + s1);          //  比较标准
}
void Fast_short(vector<string>&NumStrVector, int begin, int end, bool(*compare)(const string &, const string &))
{
	if (begin<end){
		string target = NumStrVector[end];
		int    s = begin;
		for (int idx = begin; idx != end;++idx){
			if (compare(NumStrVector[idx],target))
			{
				string tmp = NumStrVector[s];
				NumStrVector[s] = NumStrVector[idx];
				NumStrVector[idx] = tmp;
				++s;	
			}
		}
		string tmp = NumStrVector[s];
		NumStrVector[s] = NumStrVector[end];
		NumStrVector[end] = tmp;
		Fast_short(NumStrVector, begin, s-1, compare);
		Fast_short(NumStrVector, s + 1, end, compare);
	}
}
string largestNumber(vector<int> &num) {
	vector<string>NumStrVector(num.size());
	for (int i = 0; i != num.size();++i){
		stringstream ss;
		ss << num[i];
		ss >> NumStrVector[i];
	}
	if (NumStrVector.size() == 1)
		return NumStrVector[0];
	Fast_short(NumStrVector,0,NumStrVector.size()-1, CompareString);
	//sort(NumStrVector.begin(), NumStrVector.end(), CompareString);
	string ResultStr;
	for_each(NumStrVector.begin(), NumStrVector.end(), [&ResultStr](const string s){ResultStr += s; });
	for (int i = 0; i != ResultStr.size();++i){        //前置0情况处理
		if (ResultStr[i] != '0')
			return ResultStr.substr(i);
	}
	return ResultStr.substr(ResultStr.size() - 1);
}