Question

504. Base 7

中文文档

Description

Given an integer num, return _a string of its base 7 representation_.

 

Example 1:

Input: num = 100
Output: "202"

Example 2:

Input: num = -7
Output: "-10"

 

Constraints:

• -107 <= num <= 107

Solutions

Solution 1

class Solution:
  def convertToBase7(self, num: int) -> str:
    if num == 0:
      return '0'
    if num < 0:
      return '-' + self.convertToBase7(-num)
    ans = []
    while num:
      ans.append(str(num % 7))
      num //= 7
    return ''.join(ans[::-1])

class Solution {
  public String convertToBase7(int num) {
    if (num == 0) {
      return "0";
    }
    if (num < 0) {
      return "-" + convertToBase7(-num);
    }
    StringBuilder sb = new StringBuilder();
    while (num != 0) {
      sb.append(num % 7);
      num /= 7;
    }
    return sb.reverse().toString();
  }
}

class Solution {
public:
  string convertToBase7(int num) {
    if (num == 0) return "0";
    if (num < 0) return "-" + convertToBase7(-num);
    string ans = "";
    while (num) {
      ans = to_string(num % 7) + ans;
      num /= 7;
    }
    return ans;
  }
};

func convertToBase7(num int) string {
  if num == 0 {
    return "0"
  }
  if num < 0 {
    return "-" + convertToBase7(-num)
  }
  ans := []byte{}
  for num != 0 {
    ans = append([]byte{'0' + byte(num%7)}, ans...)
    num /= 7
  }
  return string(ans)
}

function convertToBase7(num: number): string {
  if (num == 0) {
    return '0';
  }
  let res = '';
  const isMinus = num < 0;
  if (isMinus) {
    num = -num;
  }
  while (num != 0) {
    const r = num % 7;
    res = r + res;
    num = (num - r) / 7;
  }
  return isMinus ? '-' + res : res;
}

impl Solution {
  pub fn convert_to_base7(mut num: i32) -> String {
    if num == 0 {
      return String::from("0");
    }
    let mut res = String::new();
    let is_minus = num < 0;
    if is_minus {
      num = -num;
    }
    while num != 0 {
      res.push_str((num % 7).to_string().as_str());
      num /= 7;
    }
    if is_minus {
      res.push('-');
    }
    res.chars().rev().collect()
  }
}