[LeetCode] Largest Number

 

Given a list of non negative integers, arrange them such that they form the largest number.

Example 1:

Input: [10,2]
Output: "210"

Example 2:

Input: [3,30,34,5,9]
Output: "9534330"

Note: The result may be very large, so you need to return a string instead of an integer.

 思路：将数组按照拼接结果排序（自定义）。然后考虑排序后数组首字母为0的情况。逐个对排序后数组元素相加即可。

class Solution {
public:
    static bool cmp(int a, int b)
    {
        string s1 = to_string(a);
        string s2 = to_string(b);
        return s1 + s2 > s2 + s1;
    }
    
    string largestNumber(vector<int>& nums) {
        string res;
        if (nums.empty())
            return res;
        sort(nums.begin(), nums.end(), cmp);
        int i = 0;
        while (nums[i] == 0 && i < nums.size())
            i++;
        if (i == nums.size())
            return "0";
        for (int j = i; j < nums.size(); ++j)
            res += to_string(nums[j]);
        return res;
    }
};