LeetCode-179. 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.

题解：

自己写一个比较函数就行了，0值处理有点坑。

class Solution {
public:
  //当sa + sb比sb + sa大时，判断a顺序在b之前，即true，反之则false
  //这里的bool理解为a, b顺序关系，true为a在b之前，false为a在b之后
  static bool cmp(int a, int b) {
    string sa = to_string(a);
    string sb = to_string(b);
    if (sa + sb > sb + sa) {
      return true;
    }
    else {
      return false;
    }
    return true;
  }
  string largestNumber(vector<int>& nums) {
      sort(nums.begin(), nums.end(), cmp);
      string res;
      for (int i = 0; i < nums.size(); i++) {
        res += to_string(nums[i]);
      }
      while (res[0] == '0' && res.length() > 1) {
        res.erase(0, 1);
      }
      return res;
  }
};