LeetCode 1256. Encode Number Solution in Java, C++, Python & More | Explanation + Code

Description

Given a non-negative integer num, Return its encoding string.

The encoding is done by converting the integer to a string using a secret function that you should deduce from the following table:

 

Example 1:

Input: num = 23

Output: "1000"

Example 2:

Input: num = 107

Output: "101100"

 

Constraints:

<li><code>0 &lt;= num &lt;= 10^9</code></li>

Solutions

Solution 1: Bit Manipulation

We add one to num, then convert it to a binary string and remove the highest bit 1.

The time complexity is O(log n), and the space complexity is O(log n). Where n is the size of num.

PythonJavaC++GoTypeScript

class Solution: def encode(self, num: int) -> str: return bin(num + 1)[3:](code-box)

class Solution { public String encode(int num) { return Integer.toBinaryString(num + 1).substring(1); } }(code-box)

class Solution { public: string encode(int num) { bitset<32> bs(++num); string ans = bs.to_string(); int i = 0; while (ans[i] == '0') { ++i; } return ans.substr(i + 1); } };(code-box)

func encode(num int) string { num++ s := strconv.FormatInt(int64(num), 2) return s[1:] }(code-box)

function encode(num: number): string { ++num; let s = num.toString(2); return s.slice(1); }(code-box)