Test results - Codility

Tasks Details

easy

1. TapeEquilibrium

Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.

Task Score

100%

Correctness

100%

Performance

100%

A non-empty array A consisting of N integers is given. Array A represents numbers on a tape.

Any integer P, such that 0 < P < N, splits this tape into two non-empty parts: A[0], A[1], ..., A[P − 1] and A[P], A[P + 1], ..., A[N − 1].

The difference between the two parts is the value of: |(A[0] + A[1] + ... + A[P − 1]) − (A[P] + A[P + 1] + ... + A[N − 1])|

In other words, it is the absolute difference between the sum of the first part and the sum of the second part.

For example, consider array A such that:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3

We can split this tape in four places:

P = 1, difference = |3 − 10| = 7

P = 2, difference = |4 − 9| = 5

P = 3, difference = |6 − 7| = 1

P = 4, difference = |10 − 3| = 7

Write a function:

function solution(A);

that, given a non-empty array A of N integers, returns the minimal difference that can be achieved.

For example, given:

A[0] = 3 A[1] = 1 A[2] = 2 A[3] = 4 A[4] = 3

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 [−1,000..1,000].

Solution

Programming language used JavaScript

Time spent on task 15 minutes

Notes

not defined yet

Code: 20:29:33 UTC, js, verify, result: Failed

show code in pop-up

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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 4.0.0)
    var lower = [];
    var upper = [];
    
    for(var i=1; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        lower[i] = lower[i-1] + A[i-1];
        upper[iRev] = upper[iRev+1] + A[i+1];
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.177 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

lower, upper: [ , NaN, NaN, NaN, NaN ] [ NaN, NaN, NaN, NaN ]

Code: 20:30:16 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 18 19

// 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 4.0.0)
    var lower = [];
    var upper = [];
    
    lower.push(0);
    
    for(var i=1; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        lower[i] = lower[i-1] + A[i-1];
        upper[iRev] = upper[iRev+1] + A[i+1];
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.220 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ NaN, NaN, NaN, NaN ]

Code: 20:31:25 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 18 19 20 21 22 23 24 25 26 27 28

// 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 4.0.0)
    var lower = [];
    var upper = [];
    
    lower.push(0);
    
    for(var i=1; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 1) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - i - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[i+1];
        }
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.175 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

lower, upper: [ 0, 0, 1, 3, 7 ] [ 0, 0, 0, 0 ]

Code: 20:31:43 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 18 19 20 21 22 23 24 25 26 27 28

// 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 4.0.0)
    var lower = [];
    var upper = [];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - i - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[i+1];
        }
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.175 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ 0, 0, 0, 0, 0 ]

Code: 20:31:53 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 18 19 20 21 22 23 24 25 26 27 28

// 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 4.0.0)
    var lower = [];
    var upper = [];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - i - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.175 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ 0, 0, 0, 0, 0 ]

Code: 20:32:57 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 18 19 20 21 22 23 24 25 26 27 28 29 30

// 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 4.0.0)
    var lower = [];
    var upper = [];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        console.log('i, iRev:', i, iRev);
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - i - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.176 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

i, iRev: 0 4
i, iRev: 1 3
i, iRev: 2 2
i, iRev: 3 1
i, iRev: 4 0
lower, upper: [ 0, 3, 4, 6, 10 ] [ 0, 0, 0, 0, 0 ]

Code: 20:33:53 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 18 19 20 21 22 23 24 25 26 27 28 29 30

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        console.log('i, iRev:', i, iRev);
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - i - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.177 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

i, iRev: 0 4
i, iRev: 1 3
i, iRev: 2 2
i, iRev: 3 1
i, iRev: 4 0
lower, upper: [ 0, 3, 4, 6, 10 ] [ 0, 0, 0, 0, 0 ]

Code: 20:34:22 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 18 19 20 21 22 23 24 25 26 27 28 29 30

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        console.log('i, iRev:', i, iRev);
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    console.log('lower, upper:', lower, upper);
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

0.177 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

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

stdout:

i, iRev: 0 4
i, iRev: 1 3
i, iRev: 2 2
i, iRev: 3 1
i, iRev: 4 0
lower, upper: [ 0, 3, 4, 6, 10 ] [ 10, 9, 7, 3, 0 ]

Code: 20:36:31 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 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    var result = Math.abs(lower[0] - upper[0]);
    
    for(var i=1; i<lower.length; i++) {
        var diff = lower[i] - upper[i];
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got -6 expected 1

0.168 s

WRONG ANSWER, got -6 expected 1

Code: 20:36:51 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 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    var result = Math.abs(lower[0] - upper[0]);
    
    for(var i=1; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.166 s

WRONG ANSWER, got 3 expected 1

Code: 20:37:32 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 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.
// console.log('this is a debug message');

function solution(A) {
    // write your code in JavaScript (Node.js 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = 0;
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev+1];
        }        
    }
    
    var result = Math.abs(lower[0] - upper[0]);
    
    console.log('lower, upper:', lower, upper);
    
    for(var i=1; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got 3 expected 1

0.180 s

WRONG ANSWER, got 3 expected 1

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ 10, 9, 7, 3, 0 ]

Code: 20:37:58 UTC, js, verify, result: Passed

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

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = A[iRev];
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev];
        }        
    }
    
    var result = Math.abs(lower[0] - upper[0]);
    
    console.log('lower, upper:', lower, upper);
    
    for(var i=1; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.204 s

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ 13, 10, 9, 7, 3 ]

Code: 20:38:29 UTC, js, verify, result: Passed

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

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = A[iRev];
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev];
        }        
    }
    
    var result = Math.abs(lower[1] - upper[1]);
    
    console.log('lower, upper:', lower, upper);
    
    for(var i=2; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.182 s

stdout:

lower, upper: [ 0, 3, 4, 6, 10 ] [ 13, 10, 9, 7, 3 ]

Code: 20:38:51 UTC, js, verify, result: Passed

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

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = A[iRev];
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev];
        }        
    }
    
    var result = Math.abs(lower[1] - upper[1]);
    
    //console.log('lower, upper:', lower, upper);
    
    for(var i=2; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.167 s

Code: 20:39:28 UTC, js, verify, result: Passed

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

// 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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = A[iRev];
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev];
        }        
    }
    
    var result = Math.abs(lower[1] - upper[1]);
    
    for(var i=2; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis

expand all Example tests

▶

example
example test

✔

0.167 s

Code: 20:39:30 UTC, js, final, score: 100

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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 4.0.0)
    var lower = [A.length];
    var upper = [A.length];
    
    lower.push(0);
    
    for(var i=0; i<A.length; i++) {
        var iRev = A.length - i - 1;
        
        if(i === 0) {
            lower[i] = 0;
        } else {
            lower[i] = lower[i-1] + A[i-1];
        }       
        
        if(iRev === A.length - 1) {
            upper[iRev] = A[iRev];
        } else {
            upper[iRev] = upper[iRev+1] + A[iRev];
        }        
    }
    
    var result = Math.abs(lower[1] - upper[1]);
    
    for(var i=2; i<lower.length; i++) {
        var diff = Math.abs(lower[i] - upper[i]);
        if(diff < result) {
            result = diff;
        }
    }
    
    return result;
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N)

expand all Example tests

▶

example
example test

✔

0.167 s

expand all Correctness tests

▶

double
two elements

✔

0.165 s

▶

simple_positive
simple test with positive numbers, length = 5

✔

0.165 s

▶

simple_negative
simple test with negative numbers, length = 5

✔

0.166 s

▶

small_random
random small, length = 100

✔

0.167 s

▶

small_range
range sequence, length = ~1,000

✔

0.175 s

▶

small
small elements

✔

0.166 s

expand all Performance tests

▶

medium_random1
random medium, numbers from 0 to 100, length = ~10,000

✔

0.183 s

▶

medium_random2
random medium, numbers from -1,000 to 50, length = ~10,000

✔

0.185 s

▶

large_ones
large sequence, numbers from -1 to 1, length = ~100,000

✔

0.230 s

▶

large_random
random large, length = ~100,000

✔

0.237 s

0.239 s

▶

large_sequence
large sequence, length = ~100,000

✔

0.209 s

▶

large_extreme
large test with maximal and minimal values, length = ~100,000

✔

0.235 s

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