Test results - Codility

Tasks Details

medium

1. MinAvgTwoSlice

Find the minimal average of any slice containing at least two elements.

Task Score

100%

Correctness

100%

Performance

100%

A non-empty array A consisting of N integers is given. A pair of integers (P, Q), such that 0 ≤ P < Q < N, is called a slice of array A (notice that the slice contains at least two elements). The average of a slice (P, Q) is the sum of A[P] + A[P + 1] + ... + A[Q] divided by the length of the slice. To be precise, the average equals (A[P] + A[P + 1] + ... + A[Q]) / (Q − P + 1).

For example, array A such that:

A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8

contains the following example slices:

slice (1, 2), whose average is (2 + 2) / 2 = 2;

slice (3, 4), whose average is (5 + 1) / 2 = 3;

slice (1, 4), whose average is (2 + 2 + 5 + 1) / 4 = 2.5.

The goal is to find the starting position of a slice whose average is minimal.

Write a function:

function solution($A);

that, given a non-empty array A consisting of N integers, returns the starting position of the slice with the minimal average. If there is more than one slice with a minimal average, you should return the smallest starting position of such a slice.

For example, given array A such that:

A[0] = 4 A[1] = 2 A[2] = 2 A[3] = 5 A[4] = 1 A[5] = 5 A[6] = 8

the function should return 1, as explained above.

Write an efficient algorithm for the following assumptions:

N is an integer within the range [2..100,000];

each element of array A is an integer within the range [−10,000..10,000].

Solution

Programming language used PHP

Time spent on task 36 minutes

Notes

not defined yet

Code: 21:29:22 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    array_push($P, $A[2] + $P[2]);
    var_dump ($P);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.056 s

RUNTIME ERROR, tested program terminated unexpectedly

stdout:

array(4) {
  [0]=>
  int(0)
  [1]=>
  int(4)
  [2]=>
  int(6)
  [3]=>
  int(8)
}
Invalid result type, int expected.

Code: 21:31:19 UTC, php, verify, result: Failed

show code in pop-up

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

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    var_dump ($min_avg);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.060 s

RUNTIME ERROR, tested program terminated unexpectedly

stdout:

int(3)
Invalid result type, int expected.

Code: 21:35:55 UTC, php, 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 18 19 20 21 22 23 24 25 26

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i] - $P[$i-1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i] - $P[$i-1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 4 expected 1

0.052 s

WRONG ANSWER, got 4 expected 1

Code: 21:37:10 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        
        if (($P[$i] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i] - $P[$i-1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i] - $P[$i-1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
        array_push($P, $A[$i] + $P[$i]);
    }
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 4 expected 1

0.048 s

WRONG ANSWER, got 4 expected 1

Code: 21:38:39 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1] - $P[$i])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1] - $P[$i])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.064 s

WRONG ANSWER, got 3 expected 1

Code: 21:38:56 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1] - $P[$i])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1] - $P[$i])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg;
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.064 s

RUNTIME ERROR, tested program terminated unexpectedly

stdout:

Invalid result type, int expected.

Code: 21:39:18 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1] - $P[$i])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1] - $P[$i])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($min_avg);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.056 s

WRONG ANSWER, got 3 expected 1

stdout:

float(-2.6666666666667)

Code: 21:39:48 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1] - $P[$i])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1] - $P[$i])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($P);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.064 s

WRONG ANSWER, got 3 expected 1

stdout:

array(8) {
  [0]=>
  int(0)
  [1]=>
  int(4)
  [2]=>
  int(6)
  [3]=>
  int(8)
  [4]=>
  int(13)
  [5]=>
  int(14)
  [6]=>
  int(19)
  [7]=>
  int(27)
}

Code: 21:40:18 UTC, php, 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 18 19 20 21 22 23 24 25 26 27

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($P);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.056 s

WRONG ANSWER, got 3 expected 1

stdout:

array(8) {
  [0]=>
  int(0)
  [1]=>
  int(4)
  [2]=>
  int(6)
  [3]=>
  int(8)
  [4]=>
  int(13)
  [5]=>
  int(14)
  [6]=>
  int(19)
  [7]=>
  int(27)
}

Code: 21:40:42 UTC, php, 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 18 19 20 21 22 23 24 25 26 27

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($min_avg);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.068 s

WRONG ANSWER, got 3 expected 1

stdout:

float(0.5)

Code: 21:41:08 UTC, php, verify, result: Failed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-1])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($min_avg);
    var_dump ($P);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.060 s

WRONG ANSWER, got 3 expected 1

stdout:

float(0.5)
array(8) {
  [0]=>
  int(0)
  [1]=>
  int(4)
  [2]=>
  int(6)
  [3]=>
  int(8)
  [4]=>
  int(13)
  [5]=>
  int(14)
  [6]=>
  int(19)
  [7]=>
  int(27)
}

Code: 21:42:16 UTC, php, verify, result: Passed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
    }
    var_dump ($min_avg);
    var_dump ($P);
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.060 s

stdout:

WARNING: producing output may seriously slow down your code!
int(2)
array(8) {
  [0]=>
  int(0)
  [1]=>
  int(4)
  [2]=>
  int(6)
  [3]=>
  int(8)
  [4]=>
  int(13)
  [5]=>
  int(14)
  [6]=>
  int(19)
  [7]=>
  int(27)
}

Code: 21:42:27 UTC, php, verify, result: Passed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.060 s

Code: 21:42:34 UTC, php, verify, result: Passed

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg_idx;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.056 s

Code: 21:42:36 UTC, php, final, score: 100

show code in pop-up

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

function solution($A) {
    $n = count($A);
    $P = array(0);
    array_push($P, $A[0]);
    array_push($P, $A[1] + $P[1]);
    //array_push($P, $A[2] + $P[2]);
    
    $min_avg_idx = 0;
    $min_avg = $P[2]/2;
    
    for ($i = 2; $i<$n; $i++) {
        array_push($P, $A[$i] + $P[$i]);
        if (($P[$i+1] - $P[$i-1])/2<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-1])/2;
            $min_avg_idx = $i-1;
        }
        if (($P[$i+1] - $P[$i-2])/3<$min_avg) {
            $min_avg = ($P[$i+1] - $P[$i-2])/3;
            $min_avg_idx = $i-2;
        }
    }
    return  $min_avg_idx;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.056 s

expand all Correctness tests

▶

double_quadruple
two or four elements

✔

0.060 s

▶

simple1
simple test, the best slice has length 3

✔

0.064 s

▶

simple2
simple test, the best slice has length 3

✔

0.060 s

▶

small_random
random, length = 100

✔

0.056 s

▶

medium_range
increasing, decreasing (legth = ~100) and small functional

✔

0.056 s

expand all Performance tests

▶

medium_random
random, N = ~700

✔

0.060 s

▶

large_ones
numbers from -1 to 1, N = ~100,000

✔

0.340 s

▶

large_random
random, N = ~100,000

✔

0.424 s

▶

extreme_values
all maximal values, N = ~100,000

✔

0.420 s

▶

large_sequence
many seqeneces, N = ~100,000

✔

0.320 s