Formatted question description: https://leetcode.ca/all/504.html
504. Base 7
Level
Easy
Description
Given an integer, return its base 7 string representation.
Example 1:
Input: 100
Output: “202”
Example 2:
Input: -7
Output: “-10”
Note: The input will be in range of [-1e7, 1e7].
Solution
If nums is 0, simply return “0”.
Otherwise, split the sign out and deal with the absolute value of num. Each time divide num by 7 and store the remainders in the reverse order until num becomes 0. If num is negative initially, add the negative sign. Finally return the string of base 7 representation.
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class Solution { public String convertToBase7(int num) { if (num == 0) return "0"; int sign = num >= 0 ? 1 : -1; num = Math.abs(num); StringBuffer base7 = new StringBuffer(); while (num > 0) { int remainder = num % 7; base7.insert(0, (char) (remainder + '0')); num /= 7; } if (sign < 0) base7.insert(0, '-'); return base7.toString(); } } -
// OJ: https://leetcode.com/problems/base-7/ // Time: O(logN) // Space: O(logN) class Solution { public: string convertToBase7(int n) { if (n == 0) return "0"; string ans; bool neg = false; if (n < 0) n = -n, neg = true; while (n) { ans += '0' + n % 7; n /= 7; } if (neg) ans += '-'; reverse(begin(ans), end(ans)); return ans; } }; -
class Solution(object): def convertToBase7(self, num): """ :type num: int :rtype: str """ def convertHelper(num, base): sign = "" if num < 0: sign = "-" num = abs(num) ans = 0 unit = 1 while num: ans += (num % base) * unit num /= base unit *= 10 return sign + str(ans) return convertHelper(num, 7)