### MaxProfit

February 08, 2020

An array A consisting of N integers is given. It contains daily prices of a stock share for a period of N consecutive days. If a single share was bought on day P and sold on day Q, where **0 ≤ P ≤ Q < N**, then the profit of such transaction is equal to A[Q] − A[P], provided that A[Q] ≥ A[P]. Otherwise, the transaction brings loss of A[P] − A[Q].

For example, consider the following array A consisting of six elements such that:

A[0] = 23171

A[1] = 21011

A[2] = 21123

A[3] = 21366

A[4] = 21013

A[5] = 21367

If a share was bought on day 0 and sold on day 2, a loss of 2048 would occur because A[2] − A[0] = 21123 − 23171 = −2048. If a share was bought on day 4 and sold on day 5, a profit of 354 would occur because A[5] − A[4] = 21367 − 21013 = 354. Maximum possible profit was 356. It would occur if a share was bought on day 1 and sold on day 5.

**Write a function**,

function solution(A);

that, given an array A consisting of N integers containing daily prices of a stock share for a period of N consecutive days, returns the maximum possible profit from one transaction during this period. The function should return 0 if it was impossible to gain any profit.

For example, given array A consisting of six elements such that:

A[0] = 23171

A[1] = 21011

A[2] = 21123

A[3] = 21366

A[4] = 21013

A[5] = 21367

the function should return 356, as explained above.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [0..400,000];

• each element of array A is an integer within the range [0..200,000].

```
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
if(A.length<2) return 0
let min = A[0]
let max = 0
let d
for(let i=0; i<A.length; i++){
if(A[i]<min) min=A[i]
d = A[i]-min
if(d>0 && d>max) max=d
}
return max
}
```