Test results - Codility

Tasks Details

medium

1. FlippingMatrix

A matrix of binary values is given. We can flip the values in selected columns. What is the maximum number of rows that we can obtain that contain all the same values?

Task Score

100%

Correctness

100%

Performance

100%

Matrix A, consisting of N rows and M columns, is given, with each cell containing the value 0 or 1. Rows are numbered from 0 to N−1 (from top to bottom). Columns are numbered from 0 to M−1 (from left to right). The values inside the matrix can be changed: you can select as many columns as you want, and in the selected column(s), every value will be flipped (from 0 to 1, or from 1 to 0).

The goal is to obtain the maximum number of rows whose contents are all the same value (that is, we count rows with all 0s and rows with all 1s).

Write a function:

function solution($A);

that, given matrix A, returns the maximum number of rows containing all the same values that can be obtained after flipping the selected columns.

Examples:

1. Given matrix A with N = 3 rows and M = 4 columns:

The picture describes the first example test.

the function should return 2. After flipping the values in column 1, the two last rows contain all equal values. Row 1 contains all 0s and row 2 contains all 1s.

2. Given matrix A with N = 4 rows and M = 4 columns:

The picture describes the second example test.

the function should return 4. After flipping the values in two of the columns (columns 0 and 2), all the rows have the same value. Rows number 0 and 2 contain all 1s, and rows number 1 and 3 contain all 0s.

Write an efficient algorithm for the following assumptions:

N and M are integers within the range [1..100,000];

N * M is not greater than 100,000.

Solution

Programming language used PHP

Total time used 45 minutes

Effective time used 45 minutes

Notes

not defined yet

Task timeline

Code: 12:05:36 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: 12:05:42 UTC, php, autosave

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    // write your code in PHP7.0
}

Code: 12:42:12 UTC, php, autosave

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1 2 3 4 5 6 7 8

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    
}

Code: 12:42:42 UTC, php, autosave

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $M=sizeof($A);
    $
    
}

Code: 12:42:53 UTC, php, 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.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $N=sizeof($A);
    $N=
    
}

Code: 12:43:07 UTC, php, verify, result: Failed

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $N=sizeof($A);
    $M=sizeof($A[0]);
    
    echo $M." ".$N;exit();
    
}

Analysis

expand all Example tests

▶

example_1
First example.

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.012 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Error during output processing. Make sure your program returns a value of correct type.

stdout:

4 3

▶

example_2
Second example.

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.008 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Error during output processing. Make sure your program returns a value of correct type.

stdout:

4 4

Code: 12:43:36 UTC, php, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $N=sizeof($A);
    $M=sizeof($A[0]);
    
    
    
}

Code: 12:44:06 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $N; $)
    
}

Code: 12:44:16 UTC, php, autosave

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

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    
    
}

Code: 12:44:30 UTC, php, autosave

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r=array()
    }
    
}

Code: 12:45:06 UTC, php, autosave

show code in pop-up

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

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r=array();
    }
    
}

Code: 12:45:18 UTC, php, autosave

show code in pop-up

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

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r=array();
        for($j=0; $j< $m; $j++)
    }
    
}

Code: 12:45:48 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
            {
                $r0[]=$j;
                $
            }
    }
    
}

Code: 12:45:58 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
            {
                $r0[]=$j;
                $r1
            }
    }
    
}

Code: 12:46:20 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
    }
    
}

Code: 12:46:30 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        $r0=
    }
    
}

Code: 12:47:00 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $)
    }
    
}

Code: 12:47:30 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]
    }
    
}

Code: 12:47:42 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
    }
    
}

Code: 12:47:55 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
    }
    
}

Code: 12:48:05 UTC, php, autosave

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
}

Code: 12:48:19 UTC, php, verify, result: Failed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    foreach($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    print_r($res);
    
}

Analysis

expand all Example tests

▶

example_1
First example.

✘

RUNTIME ERROR
tested program terminated with exit code 255

0.004 s

RUNTIME ERROR, tested program terminated with exit code 255

stderr:

PHP Parse error:  syntax error, unexpected ';' in func.php on line 10
Parse error: syntax error, unexpected ';' in func.php on line 10

▶

example_2
Second example.

✘

RUNTIME ERROR
tested program terminated with exit code 255

0.004 s

RUNTIME ERROR, tested program terminated with exit code 255

stderr:

PHP Parse error:  syntax error, unexpected ';' in func.php on line 10
Parse error: syntax error, unexpected ';' in func.php on line 10

Code: 12:48:36 UTC, php, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    fore($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    print_r($res);
    
}

Code: 12:48:39 UTC, php, verify, result: Failed

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    for($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    print_r($res);
    
}

Analysis

expand all Example tests

▶

example_1
First example.

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.008 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected (got NULL)

stdout:

Array
(
    [0,1,2,3] => 1
    [-] => 1
    [0,2,3] => 2
    [1] => 2
)

▶

example_2
Second example.

✘

RUNTIME ERROR
tested program terminated with exit code 1

0.008 s

RUNTIME ERROR, tested program terminated with exit code 1

stderr:

Invalid result type, int expected (got NULL)

stdout:

Array
(
    [0,2] => 4
    [1,3] => 4
)

Code: 12:49:06 UTC, php, autosave

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    for($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    f
    
}

Code: 12:49:31 UTC, php, verify, result: Passed

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    for($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    $max=1;
    foreach($res as $r)
        if($r > $max)
            $max=$r;
    
    return $max;   
}

Analysis

expand all Example tests

▶

example_1
First example.

✔

0.008 s

▶

example_2
Second example.

✔

0.004 s

Code: 12:49:38 UTC, php, verify, result: Passed

show code in pop-up

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    for($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    $max=1;
    foreach($res as $r)
        if($r > $max)
            $max=$r;
    
    return $max;   
}

Analysis

expand all Example tests

▶

example_1
First example.

✔

0.004 s

▶

example_2
Second example.

✔

0.004 s

Code: 12:49:40 UTC, php, final, score: 100

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// you can write to stdout for debugging purposes, e.g.
// print "this is a debug message\n";

function solution($A) {
    $res=array();
    
    $n=sizeof($A);
    $m=sizeof($A[0]);
    
    for($i=0; $i< $n; $i++)
    {
        $r0=array();
        $r1=array();
        for($j=0; $j< $m; $j++)
            if($A[$i][$j])
                $r1[]=$j;
            else
                $r0[]=$j;
        
        if($r0)
            $r0=implode(",", $r0);
        else
            $r0="-";
        if(isset($res[$r0]))
            $res[$r0]++;
        else
            $res[$r0]=1;
        
        if($r1)
            $r1=implode(",", $r1);
        else
            $r1="-";
        if(isset($res[$r1]))
            $res[$r1]++;
        else
            $res[$r1]=1;
    }
    
    $max=1;
    foreach($res as $r)
        if($r > $max)
            $max=$r;
    
    return $max;   
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N*M*log(N+M)) or O(N*M)

expand all Example tests

▶

example_1
First example.

✔

0.004 s

▶

example_2
Second example.

✔

0.004 s

expand all Correctness tests

▶

one_row
1 row, 5 columns.

✔

0.004 s

▶

one_column
5 rows, 1 column.

✔

0.004 s

▶

2_x_2
2 row, 2 columns.

✔

0.004 s

▶

small_diagonal
Each row contains no more than one occurrence of 1.

✔

0.004 s

▶

small_random
Random matrix, NM <= 40.

✔

0.004 s

▶

medium_diagonal
Each row contains no more than one occurrence of 1, NM <= 1,600.

✔

0.004 s

0.008 s

0.004 s

▶

medium_random
Random matrix, NM <= 2,500.

✔

0.004 s

0.008 s

expand all Performance tests

▶

large_diagonal
Each row contains no more than one occurrence of 1, NM <= 100,000.

✔

0.028 s

0.032 s

0.040 s

▶

large_random
Random matrix, NM <= 100,000.

✔

0.032 s

0.040 s

▶

large_one_row
1 row, 100,000 columns.

✔

0.036 s

▶

large_one_column
100,000 row, 1 column.

✔

0.096 s