LeetCode179. Largest Number

一、题目

Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.

Since the result may be very large, so you need to return a string instead of an integer.

Example 1:

Input: nums = [10,2]
Output: “210”
Example 2:

Input: nums = [3,30,34,5,9]
Output: “9534330”

Constraints:

1 <= nums.length <= 100
0 <= nums[i] <= 109

二、题解

对于a，b。若a+b的字典序大于b+a的字典序，则a+b排在b+a前面

class Solution {
public:
    static bool cmp(string left,string right){
        return left + right > right + left;
    }
    string largestNumber(vector<int>& nums) {
        int n = nums.size();
        vector<string> str;
        for(int i = 0;i < n;i++){
            str.push_back(to_string(nums[i]));
        }
        sort(str.begin(),str.end(),cmp);
        string res = "";
        for(int i = 0;i < str.size();i++) res += str[i];
        if(res[0] == '0') return "0";
        return res;
    }
};