Leetcode: Largest Number (sort)

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.

----------------------------------------

----------------------------------------

1. using string type of x+y>y+x to decide the order of x and y. If x+y>y+x is true, x should be put in front; If not, y should be put in front. Here a self made sort function is used. 

2. then concatenate the string together

/////////////////////////////////

//code

class Solution {

public:

       //self made comparison 

       static bool comp(int a, int b){

              string x = to_string(a), y = to_string(b);

              return x + y>y + x;

       }

       string largestNumber(vector<int>& nums) {

              //sort the nums according to above comparison 

              sort(nums.begin(), nums.end(), comp);

              //convert to string

              string res = "";

              for (int i = 0; i<nums.size(); i++){

                   res += to_string(nums[i]);//concatenate the string

              }

              if (res[0] == '0') res = '0';

              return res;

       }

};