Tasks Details
medium
Find the smallest positive integer that does not occur in a given sequence.
Task Score
100%
Correctness
100%
Performance
100%
This is a demo task.
Write a function:
function solution(A);
that, given an array A of N integers, returns the smallest positive integer (greater than 0) that does not occur in A.
For example, given A = [1, 3, 6, 4, 1, 2], the function should return 5.
Given A = [1, 2, 3], the function should return 4.
Given A = [−1, −3], the function should return 1.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [1..100,000];
- each element of array A is an integer within the range [−1,000,000..1,000,000].
Copyright 2009–2025 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used JavaScript
Time spent on task 18 minutes
Notes
not defined yet
Code: 13:35:52 UTC,
java,
autosave
Code: 13:45:13 UTC,
js,
autosave
Code: 13:45:36 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
}
Code: 13:51:33 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 0; i < 10; ++i) {
set.set(A[i])
}
}
Code: 13:51:45 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 0; i < 10000000; ++i) {
}
}
Code: 13:51:59 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 0; i < 10000000; ++i) {
if (set.has(i))
}
}
Code: 13:52:09 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 1; i < 10000000; ++i) {
if (set.has(i))
}
}
Code: 13:52:27 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i
}
}
return -1;
}
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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
1.
0.080 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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: 13:52:32 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.set(A[i])
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i;
}
}
return 1;
}
Analysis
expand all
Example tests
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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
1.
0.072 s
RUNTIME ERROR,
tested program terminated with exit code 1
stderr:
TypeError: set.set is not a function at solution (solution.js:10:13) 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: 13:52:40 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.(A[i])
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i;
}
}
return 1;
}
Code: 13:52:42 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.add(A[i])
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i;
}
}
return 1;
}
Analysis
Code: 13:52:47 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.add(A[i]);
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i;
}
}
return 1;
}
Analysis
Code: 13:52:50 UTC,
js,
final,
score: 
100
// 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 set = new Set();
for(let i = 0; i < A.length; ++i) {
set.add(A[i]);
}
for(let i = 1; i < 10000000; ++i) {
if (!set.has(i)) {
return i;
}
}
return 1;
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
0.072 s
OK
2.
0.072 s
OK
3.
0.072 s
OK
4.
0.072 s
OK
1.
0.072 s
OK
2.
0.072 s
OK
3.
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
expand all
Performance tests
1.
0.092 s
OK
2.
0.096 s
OK
3.
0.096 s
OK
1.
0.132 s
OK
1.
0.148 s
OK
2.
0.144 s
OK
1.
0.120 s
OK