179. Largest Number

Total Accepted: 65867
Total Submissions: 304513
Difficulty: Medium
Contributors: Admin

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.

Credits:

来源： https://leetcode.com/problems/largest-number/

分析

关键在于怎样判断两个数字组合谁放在前面。

判断规则是将a和b组成"ab" 和 "ba"，哪个更大，说明首个数字更大

class Solution {
public:
    string largestNumber(vector<int>& nums) {
        sort(nums.begin(), nums.end(),[](int a, int b){
            return to_string(a) + to_string(b) > to_string(b) + to_string(a);
        });
        string result;
        for(auto n: nums){
            result+= to_string(n);
        }
        // in case all the number in nums is '0'
        return result[0] == '0' ? "0" : result;
    }
};

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