feat: add LeetCode problem 69

[Asp-irin]

Here i am with the two methods,use can use accordingly as your wish,all suggestions and critics are accepted

Description of Change

References

Checklist

• Added description of change
• Added file name matches File name guidelines
• Added tests and example, test must pass
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• Search previous suggestions before making a new one, as yours may be a duplicate.
• I acknowledge that all my contributions will be made under the project's license.

Notes:

[alexpantyukhin]

Please follow the https://github.com/TheAlgorithms/C/tree/master/leetcode#-adding-a-new-solution- doc. Actually you have to put the solution which could be run on the leetcode. Your solution will fall because of it contain 2 declarations of the int mySqrt(int x){.