【LeetCode #179】Largest Number 解题报告

原题链接：Largest Number

题目描述：

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.

Solution：

易忽略全为0的情况

字符串比较算法

tostring()的运用

sort函数

代码：

class Solution
{
public:
//比较函数
static bool compare(string s1, string s2)
{
return (s1 + s2) > (s2 + s1);
}

string largestNumber(vector<int>& nums)
{
if(nums.empty())
return "";

vector<string> strNums;

vector<int>::const_iterator iter = nums.begin();
while (iter != nums.end())
{
//把整形转换成字符串类型
strNums.push_back(to_string((long long)*iter));
iter ++;
}

//借用sort函数对转换后的数字字符串排序
sort(strNums.begin(), strNums.end(),compare);

string res = "";
vector<string>::const_iterator it = strNums.begin();
while(it != strNums.end())
{
res.append(*it);
it ++;
}

//输入的非负整数全部为0的情况下，输出一个0
int index = 0;
while (index < res.length() && res[index] == '0')
index ++;

if (index == res.length())
return "0";

return res;
}
};