leetcode 179. 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.

一开始写了半天比较函数，后来反应过来，可以用字符串相加后比较来确定 a串还是b串对总大小的贡献大小

写个比较函数就可以了，注意0的情况。

class Solution {
public:
    static bool cmp(const string& a, const string& b) {
        return (a+b) > (b+a);
    }
    string largestNumber(vector<int>& nums) {
        vector<string> v;
        int sum = 0;
        for (int i = 0; i < nums.size(); ++i) {
            v.push_back(to_string(nums[i]));
            sum += nums[i];
        }
        if (sum == 0) return "0";
        sort(v.begin(), v.end(), cmp);
        string k = "";
        for (int i = 0; i < nums.size(); ++i) {
            k += v[i];
        }
        return k;
    }
};