Test results - Codility

Tasks Details

easy

1. BinaryGap

Find longest sequence of zeros in binary representation of an integer.

100%

Not assessed

A binary gap within a positive integer N is any maximal sequence of consecutive zeros that is surrounded by ones at both ends in the binary representation of N.

For example, number 9 has binary representation 1001 and contains a binary gap of length 2. The number 529 has binary representation 1000010001 and contains two binary gaps: one of length 4 and one of length 3. The number 20 has binary representation 10100 and contains one binary gap of length 1. The number 15 has binary representation 1111 and has no binary gaps. The number 32 has binary representation 100000 and has no binary gaps.

Write a function:

function solution(N);

that, given a positive integer N, returns the length of its longest binary gap. The function should return 0 if N doesn't contain a binary gap.

For example, given N = 1041 the function should return 5, because N has binary representation 10000010001 and so its longest binary gap is of length 5. Given N = 32 the function should return 0, because N has binary representation '100000' and thus no binary gaps.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [1..2,147,483,647].

Solution

Programming language used JavaScript

Time spent on task 2 minutes

Notes

not defined yet

Task timeline

Code: 05:57:31 UTC, js, verify, result: Passed

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

function solution(N) {
    const bin = N.toString(2);
    let max = 0;
    let gap = 0;

    bin.split("").forEach(num => {
        if(num == 1){
            max = Math.max(max, gap);
            gap=0;
        }else{
            gap++;
        }
    })

    return max;
}

Analysis

▶

example1
example test n=1041=10000010001_2

✔

▶

example2
example test n=15=1111_2

✔

▶

example3
example test n=32=100000_2

✔

Code: 05:57:37 UTC, js, verify, result: Passed

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

function solution(N) {
    const bin = N.toString(2);
    let max = 0;
    let gap = 0;

    bin.split("").forEach(num => {
        if(num == 1){
            max = Math.max(max, gap);
            gap=0;
        }else{
            gap++;
        }
    })

    return max;
}

Analysis

▶

example1
example test n=1041=10000010001_2

✔

▶

example2
example test n=15=1111_2

✔

▶

example3
example test n=32=100000_2

✔

Code: 05:57:39 UTC, js, final, score: 100

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

function solution(N) {
    const bin = N.toString(2);
    let max = 0;
    let gap = 0;

    bin.split("").forEach(num => {
        if(num == 1){
            max = Math.max(max, gap);
            gap=0;
        }else{
            gap++;
        }
    })

    return max;
}

Analysis summary

The solution obtained perfect score.

Analysis

▶

example1
example test n=1041=10000010001_2

✔

▶

example2
example test n=15=1111_2

✔

▶

example3
example test n=32=100000_2

✔

▶

extremes
n=1, n=5=101_2 and n=2147483647=2**31-1

✔

▶

trailing_zeroes
n=6=110_2 and n=328=101001000_2

✔

▶

power_of_2
n=5=101_2, n=16=2**4 and n=1024=2**10

✔

▶

simple1
n=9=1001_2 and n=11=1011_2

✔

▶

simple2
n=19=10011 and n=42=101010_2

✔

▶

simple3
n=1162=10010001010_2 and n=5=101_2

✔

▶

medium1
n=51712=110010100000000_2 and n=20=10100_2

✔

▶

medium2
n=561892=10001001001011100100_2 and n=9=1001_2

✔

▶

medium3
n=66561=10000010000000001_2

✔

▶

large1
n=6291457=11000000000000000000001_2

✔

▶

large2
n=74901729=100011101101110100011100001

✔

▶

large3
n=805306373=110000000000000000000000000101_2

✔

▶

large4
n=1376796946=1010010000100000100000100010010_2

✔

▶

large5
n=1073741825=1000000000000000000000000000001_2

✔

▶

large6
n=1610612737=1100000000000000000000000000001_2

✔