Adding two algorithms

[anubhav9199]

Adding two algorithms to the repository.

1. fractional knapsack which is a problem of dynamic programming and add to fix an issue Fractional knapsack #66 in the demand of fractional knapsack
   
2. Longest palindrome substring is a problem of dynamic programming and add in the repository by seeing the demand of the people to find the solution of the longest palindrome substring in linear time complexity. I use manacher algorithm to find the solution in the least time complexity.