1256. Encode Number

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:

• 0 <= num <= 10^9

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 $num$.

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

• 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);
}
};

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


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

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