reduce by round/single side move
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```csharp []
public class Solution {
    public int NumberOfChild(int n, int k) {
        int doubleSize = 2*(n-1);

        k %= doubleSize; // calculate less than one round

        if(k < n) // to right
            return k;

        k -= (n-1); // reduce from 0 to n-1
        return n -1 -k; // return from n-1 to rest;
    }
}
```
['C#']