If you know the future prices of a stock, what's the best time to buy and sell?

Question

Interview Question by a financial software company for a Programmer position

Q1) Say you have an array for which the ith element is the price of a giv

Answer 1

Suppose the prices are the array P = [p_1, p_2, ..., p_n]

Construct a new array A = [p_1, p_2 - p_1, p_3 - p_2, ..., p_n - p_{n-1}]

i.e A[i] = p_{i+1} - p_i, taking p_0 = 0.

Now go find the maximum sum sub-array in this.

OR

Find a different algorithm, and solve the maximum sub-array problem!

The problems are equivalent.