Tasks Details
easy
1.
MaxProfit
Given a log of stock prices compute the maximum possible earning.
Task Score
100%
Correctness
100%
Performance
100%
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] = 21367If 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] = 21367the 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].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used JavaScript
Time spent on task 3 minutes
Notes
not defined yet
Code: 05:27:53 UTC,
java,
autosave
Code: 05:28:03 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.
for(let i=A.length-1; i>=1; i--){
max = Math.max(max, maxR - A[i]);
maxR = Math.max(maxR, A[i]);
}
return max;
}
Code: 05:28:33 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight(v=>{
max = Math.max(max, maxR - A[i]);
maxR = Math.max(maxR, A[i]);
});
for(let i=A.length-1; i>=1; i--){
max = Math.max(max, maxR - A[i]);
maxR = Math.max(maxR, A[i]);
}
return max;
}
Code: 05:28:39 UTC,
js,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight(v=>{
max = Math.max(max, maxR - v);
maxR = Math.max(maxR, v);
});
return max;
}
Analysis
expand all
Example tests
1.
0.076 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
Invalid result type, integer expected, non-integer number found
Code: 05:28:49 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight((acc,v)=>{
max = Math.max(max, maxR - v);
maxR = Math.max(maxR, v);
});
return max;
}
Analysis
Code: 05:29:03 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight((max,v)=>{
max = Math.max(max, maxR - v);
maxR = Math.max(maxR, v);
},0);
return max;
}
Code: 05:29:20 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight((acc,v)=>{
max = Math.max(max, maxR - v);
maxR = Math.max(maxR, v);
},[0,]);
return max;
}
Code: 05:29:30 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
let max = 0;
let maxR = A.pop();
A.reduceRight((acc,v)=>{
max = Math.max(max, maxR - v);
maxR = Math.max(maxR, v);
},[0,A.pop()]);
return max;
}
Code: 05:29:51 UTC,
js,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
return A.reduceRight((acc,v)=>{
acc[0] = Math.max(acc[0], acc[1] - v);
acc[1] = Math.max(acc[1], v);
},[0,A.pop()])[0];
}
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: Cannot read property '0' of undefined
at A.reduceRight (solution.js:7:30)
at Array.reduceRight (<anonymous>)
at solution (solution.js:6:14)
at solutionWrapper (/tmp/exec.js:402:28)
at Promise.resolve.then (/tmp/exec.js:428:24)
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:188:7)
at Function.Module.runMain (module.js:686:11)
at startup (bootstrap_node.js:187:16)
at bootstrap_node.js:608:3
Code: 05:30:01 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
return A.reduceRight((acc,v)=>{
acc[0] = Math.max(acc[0], acc[1] - v);
acc[1] = Math.max(acc[1], v);
return acc;
},[0,A.pop()])[0];
}
Code: 05:30:02 UTC,
js,
verify,
result: Passed
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
return A.reduceRight((acc,v)=>{
acc[0] = Math.max(acc[0], acc[1] - v);
acc[1] = Math.max(acc[1], v);
return acc;
},[0,A.pop()])[0];
}
Analysis
Code: 05:30:16 UTC,
js,
autosave
// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');
function solution(A) {
// write your code in JavaScript (Node.js 8.9.4)
return A.reduceRight((acc,v)=>{
acc[0] = Math.max(acc[0], acc[1] - v);
acc[1] = Math.max(acc[1], v);
return [];
},[0,A.pop()])[0];
}
Code: 05:30:24 UTC,
js,
verify,
result: Passed
Analysis
Code: 05:30:26 UTC,
js,
verify,
result: Passed
Analysis
Code: 05:30:33 UTC,
js,
verify,
result: Passed
Analysis
Code: 05:30:38 UTC,
js,
verify,
result: Passed
Analysis
Code: 05:30:40 UTC,
js,
final,
score:
100
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N)
expand all
Correctness tests
1.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
1.
0.072 s
OK
max_profit_after_max_and_before_min
max profit is after global maximum and before global minimum
max profit is after global maximum and before global minimum
✔
OK
1.
0.072 s
OK
expand all
Performance tests
medium_1
large value (99) followed by short V-pattern (values from [1..5]) repeated 100 times
large value (99) followed by short V-pattern (values from [1..5]) repeated 100 times
✔
OK
1.
0.072 s
OK
1.
0.132 s
OK
1.
0.316 s
OK
1.
0.200 s
OK