leetcode 1404 - Number of Steps to Reduce a Number in Binary Representation to One

https://leetcode.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/
https://leetcode.com/problems/number-of-steps-to-reduce-a-number-in-binary-representation-to-one/discuss/564287/C%2B%2BJava-O(n)

Given a number s in their binary representation. Return the number of steps to reduce it to 1 under the following rules:

If the current number is even, you have to divide it by 2.

If the current number is odd, you have to add 1 to it.

It’s guaranteed that you can always reach to one for all testcases.

Example 1:

Input: s = “1101”
Output: 6
Explanation: “1101” corressponds to number 13 in their decimal representation.
Step 1) 13 is odd, add 1 and obtain 14.
Step 2) 14 is even, divide by 2 and obtain 7.
Step 3) 7 is odd, add 1 and obtain 8.
Step 4) 8 is even, divide by 2 and obtain 4.
Step 5) 4 is even, divide by 2 and obtain 2.
Step 6) 2 is even, divide by 2 and obtain 1.
Example 2:

Input: s = “10”
Output: 1
Explanation: “10” corressponds to number 2 in their decimal representation.
Step 1) 2 is even, divide by 2 and obtain 1.
Example 3:

Input: s = “1”
Output: 0

Constraints:

1 <= s.length <= 500
s consists of characters ‘0’ or ‘1’
s[0] == ‘1’

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class Solution {
public:
int numSteps(string s) {
int size = s.size();
int total = 0;
int carry = 0;

for (int i = size - 1; i > 0; i--) {
total++;

if (s[i] - '0' + carry == 1) {
carry = 1;
total++;
}
}

return total + carry;
}
};