Test results - Codility

Tasks Details

easy

1. PermMissingElem

Find the missing element in a given permutation.

Task Score

100%

Correctness

100%

Performance

100%

An array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.

Your goal is to find that missing element.

Write a function:

function solution(A);

that, given an array A, returns the value of the missing element.

For example, given array A such that:

A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5

the function should return 4, as it is the missing element.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [0..100,000];

the elements of A are all distinct;

each element of array A is an integer within the range [1..(N + 1)].

Solution

Programming language used JavaScript

Time spent on task 11 minutes

Notes

not defined yet

Task timeline

Code: 14:25:59 UTC, java, autosave

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// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
    }
}

Code: 14:26:00 UTC, java, autosave

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// you can also use imports, for example:
// import java.util.*;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
    }
}

Code: 14:26:10 UTC, js, autosave

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// 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)
}

Code: 14:30:15 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if ()
}

Code: 14:30:42 UTC, js, autosave

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1 2 3 4 5 6 7 8 9 10

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const sum = A[A.length - 1] * A[A.length - 1] + 1 / 2
}

Code: 14:31:13 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const sum = size * (size + 1)) / 2
}

Code: 14:31:18 UTC, js, verify, result: Failed

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const sum = (size * (size + 1)) / 2
    
    console.log(sum)
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.072 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, integer expected, 'undefined' found
Perhaps you are missing a 'return'?

stdout:

Code: 14:31:40 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const sum = (size * (size + 1)) / 2
    
    
}

Code: 14:32:03 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const sum = (size * (size + 1)) / 2
    
    for (let i=0; i<=A.length - 1; i++){
        sum -= A[i]
    }
}

Code: 14:32:07 UTC, js, verify, result: Failed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size * (size + 1)) / 2
    
    for (let i=0; i<=A.length - 1; i++){
        sum -= A[i]
    }
    
    return sum
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got -1 expected 4

0.068 s

WRONG ANSWER, got -1 expected 4

Code: 14:32:54 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let  = (size * (size + 1)) / 2
    
    for (let i=0; i<=A.length - 1; i++){
        sum -= A[i]
    }
    
    return sum
}

Code: 14:33:25 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const originalSum = (size * (size + 1)) / 2
    
    const sum = A.reduce((p, c) => p + c, 0)
    
    return sum - originalSum
}

Code: 14:33:26 UTC, js, verify, result: Failed

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const originalSum = (size * (size + 1)) / 2
    
    const sum = A.reduce((p, c) => p + c, 0)
    
    return sum - originalSum
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 1 expected 4

0.072 s

WRONG ANSWER, got 1 expected 4

Code: 14:33:39 UTC, js, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    const originalSum = (size * (size + 1)) / 2
    
    const sum = A.reduce((p, c) => p + c, 0)
    
    console.log(sum, originalSum)
    
    return sum - originalSum
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 1 expected 4

0.076 s

WRONG ANSWER, got 1 expected 4

stdout:

11 10

Code: 14:35:00 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
   
    
    const sum = A.reduce((p, c) => p + c, 0)
    
    console.log(sum, originalSum)
    
    return sum - originalSum
}

Code: 14:35:14 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = size + 1
    
    return sum - originalSum
}

Code: 14:35:45 UTC, js, autosave

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size + 1) * (size + 2) / 2
    
    for (let i=0; i<=size-1 i++) {
        sum -= 
    }
    
    return sum 
}

Code: 14:35:47 UTC, js, verify, result: Failed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size + 1) * (size + 2) / 2
    
    for (let i=0; i<=size-1 i++) {
        sum -= A[i]
    }
    
    return sum 
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.072 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

solution.js:12
    for (let i=0; i<=size-1 i++) {
                            ^

SyntaxError: Unexpected identifier
    at createScript (vm.js:80:10)
    at Object.runInNewContext (vm.js:135:10)
    at getSolution (/tmp/exec.js:392:29)
    at Promise.resolve.then (/tmp/exec.js:426:34)
    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: 14:35:52 UTC, js, verify, result: Passed

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// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size + 1) * (size + 2) / 2
    
    for (let i=0; i<=size-1; i++) {
        sum -= A[i]
    }
    
    return sum 
}

Analysis

expand all Example tests

▶

example
example test

✔

0.072 s

Code: 14:35:59 UTC, js, verify, result: Passed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size + 1) * (size + 2) / 2
    
    for (let i=0; i<=size-1; i++) {
        sum -= A[i]
    }
    
    return sum 
}

Analysis

expand all Example tests

▶

example
example test

✔

0.072 s

Code: 14:36:01 UTC, js, final, score: 100

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A) {
    if (!A.length) {
        return 1
    }
    
    const size = A.length
    let sum = (size + 1) * (size + 2) / 2
    
    for (let i=0; i<=size-1; i++) {
        sum -= A[i]
    }
    
    return sum 
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N) or O(N * log(N))

expand all Example tests

▶

example
example test

✔

0.072 s

expand all Correctness tests

▶

empty_and_single
empty list and single element

✔

0.068 s

0.072 s

▶

missing_first_or_last
the first or the last element is missing

✔

0.068 s

▶

single
single element

✔

0.068 s

▶

double
two elements

✔

0.068 s

0.072 s

0.068 s

▶

simple
simple test

✔

0.072 s

expand all Performance tests

▶

medium1
medium test, length = ~10,000

✔

0.080 s

▶

medium2
medium test, length = ~10,000

✔

0.080 s

▶

large_range
range sequence, length = ~100,000

✔

0.108 s

0.096 s

▶

large1
large test, length = ~100,000

✔

0.112 s

▶

large2
large test, length = ~100,000

✔

0.100 s