Question

179. 最大数

English Version

题目描述

给定一组非负整数 nums，重新排列每个数的顺序（每个数不可拆分）使之组成一个最大的整数。

注意：输出结果可能非常大，所以你需要返回一个字符串而不是整数。

 

示例 1：

输入：nums = [10,2]
输出："210"

示例 2：

输入：nums = [3,30,34,5,9]
输出："9534330"

 

提示：

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

解法

方法一：自定义排序

先转成字符串列表，再对字符串列表进行字典序降序排列。最后将列表所有字符串拼接即可。

class Solution:
  def largestNumber(self, nums: List[int]) -> str:
    nums = [str(v) for v in nums]
    nums.sort(key=cmp_to_key(lambda a, b: 1 if a + b < b + a else -1))
    return "0" if nums[0] == "0" else "".join(nums)

class Solution {
  public String largestNumber(int[] nums) {
    List<String> vs = new ArrayList<>();
    for (int v : nums) {
      vs.add(v + "");
    }
    vs.sort((a, b) -> (b + a).compareTo(a + b));
    if ("0".equals(vs.get(0))) {
      return "0";
    }
    return String.join("", vs);
  }
}

class Solution {
public:
  string largestNumber(vector<int>& nums) {
    vector<string> vs;
    for (int v : nums) vs.push_back(to_string(v));
    sort(vs.begin(), vs.end(), [](string& a, string& b) {
      return a + b > b + a;
    });
    if (vs[0] == "0") return "0";
    string ans;
    for (string v : vs) ans += v;
    return ans;
  }
};

func largestNumber(nums []int) string {
  vs := make([]string, len(nums))
  for i, v := range nums {
    vs[i] = strconv.Itoa(v)
  }
  sort.Slice(vs, func(i, j int) bool {
    return vs[i]+vs[j] > vs[j]+vs[i]
  })
  if vs[0] == "0" {
    return "0"
  }
  return strings.Join(vs, "")
}

using System;
using System.Globalization;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class Comparer: IComparer<string>
{
  public int Compare(string left, string right)
  {
    return Compare(left, right, 0, 0);
  }

  private int Compare(string left, string right, int lBegin, int rBegin)
  {
    var len = Math.Min(left.Length - lBegin, right.Length - rBegin);
    for (var i = 0; i < len; ++i)
    {
      if (left[lBegin + i] != right[rBegin + i])
      {
        return left[lBegin + i] < right[rBegin + i] ? -1 : 1;
      }
    }

    if (left.Length - lBegin == right.Length - rBegin)
    {
      return 0;
    }
    if (left.Length - lBegin > right.Length - rBegin)
    {
      return Compare(left, right, lBegin + len, rBegin);
    }
    else
    {
      return Compare(left, right, lBegin, rBegin + len);
    }
  }
}

public class Solution {
  public string LargestNumber(int[] nums) {
    var sb = new StringBuilder();
    var strs = nums.Select(n => n.ToString(CultureInfo.InvariantCulture)).OrderByDescending(s => s, new Comparer());

    var nonZeroOccurred = false;
    foreach (var str in strs)
    {
      if (!nonZeroOccurred && str == "0") continue;
      sb.Append(str);
      nonZeroOccurred = true;
    }
    return sb.Length == 0 ? "0" : sb.ToString();
  }
}