[LeetCode] 504. Base 7 基数七
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].
给一个整数，返回它的七进制数。
解法1: 迭代
解法2: 递归
Java:
public class Solution {
public String convertTo7(int num) {
if (num == 0) return "0";
StringBuilder sb = new StringBuilder();
boolean negative = false;
if (num < 0) {
negative = true;
}
while (num != 0) {
sb.append(Math.abs(num % 7));
num = num / 7;
}
if (negative) {
sb.append("-");
}
return sb.reverse().toString();
}
}
Java:
public String convertTo7(int num) {
if (num < 0)
return '-' + convertTo7(-num);
if (num < 7)
return num + "";
return convertTo7(num / 7) + num % 7;
}
Python:
class Solution(object):
def convertToBase7(self, num):
"""
:type num: int
:rtype: str
"""
if num == 0:
return '0'
if num < 0:
return '-' + self.convertToBase7(-num)
res = ''
while num > 0:
res = str(num % 7) + res
num = num / 7
return res
Python:
def convertTo7(self, num):
if num == 0: return '0'
n, res = abs(num), ''
while n:
res = str(n % 7) + res
n //= 7
return res if num > 0 else '-' + res
Python:
def convertTo7(self, num):
if num < 0: return '-' + self.convertTo7(-num)
if num < 7: return str(num)
return self.convertTo7(num // 7) + str(num % 7)
C++:
class Solution {
public:
string convertToBase7(int num) {
if (num == 0) return "0";
string res = "";
bool positive = num > 0;
while (num != 0) {
res = to_string(abs(num % 7)) + res;
num /= 7;
}
return positive ? res : "-" + res;
}
};
C++:
class Solution {
public:
string convertToBase7(int num) {
if (num < 0) return "-" + convertToBase7(-num);
if (num < 7) return to_string(num);
return convertToBase7(num / 7) + to_string(num % 7);
}
};
