Test results - Codility

Tasks Details

easy

1. Distinct

Compute number of distinct values in an array.

50%

66%

Write a function

function solution(A);

that, given an array A consisting of N integers, returns the number of distinct values in array A.

For example, given array A consisting of six elements such that:

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

the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.

Write an efficient algorithm for the following assumptions:

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

each element of array A is an integer within the range [−1,000,000..1,000,000].

Solution

Programming language used JavaScript

Time spent on task 6 minutes

Notes

not defined yet

Task timeline

Code: 21:30:25 UTC, js, verify, result: Failed

1 2 3 4 5 6 7

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    console.log(A);
}

Analysis

▶

example1
example test, positive answer

✘

RUNTIME ERROR
tested program terminated unexpectedly

Code: 21:32:51 UTC, js, verify, result: Failed

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

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    var count = 0;
    
    if(A.length == 1) return 1;
    
    for(var i=0; i<A.length-1;i++){
        if(A[i] !== A[i++]){
            count++;
        }
    }
    
    return count;
}

Analysis

▶

example1
example test, positive answer

✘

WRONG ANSWER
got 0 expected 3

Code: 21:33:20 UTC, js, verify, result: Failed

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

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    var count = 0;
    
    if(A.length == 1) return 1;
    
    for(var i=0; i<A.length-1;i++){
        if(A[i] !== A[i+1]){
            count++;
        }
    }
    
    return count;
}

Analysis

▶

example1
example test, positive answer

✘

WRONG ANSWER
got 2 expected 3

Code: 21:33:45 UTC, js, verify, result: Passed

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

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    var count = 1;
    
    if(A.length == 0) return 0;
    
    for(var i=0; i<A.length-1;i++){
        if(A[i] !== A[i+1]){
            count++;
        }
    }
    
    return count;
}

Analysis

▶

example1
example test, positive answer

✔

Code: 21:33:55 UTC, js, verify, result: Passed

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

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    var count = 1;
    
    if(A.length == 0) return 0;
    
    for(var i=0; i<A.length-1;i++){
        if(A[i] !== A[i+1]){
            count++;
        }
    }
    
    return count;
}

Analysis

▶

example1
example test, positive answer

✔

Code: 21:34:00 UTC, js, final, score: 50

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

// you can use console.log for debugging purposes, i.e.
// console.log('this is a debug message');

function solution(A) {
    A.sort(function(a,b){return a > b});
    var count = 1;
    
    if(A.length == 0) return 0;
    
    for(var i=0; i<A.length-1;i++){
        if(A[i] !== A[i+1]){
            count++;
        }
    }
    
    return count;
}

Analysis summary

The following issues have been detected: wrong answers.

Analysis

▶

example1
example test, positive answer

✔

▶

extreme_empty
empty sequence

✔

▶

extreme_single
sequence of one element

✔

▶

extreme_two_elems
sequence of three distinct elements

✔

▶

extreme_one_value
sequence of 10 equal elements

✔

▶

extreme_negative
sequence of negative elements, length=5

✔

▶

extreme_big_values
sequence with big values, length=5

✔

▶

medium1
chaotic sequence of value sfrom [0..1K], length=100

✘

WRONG ANSWER
got 99 expected 96

▶

medium2
chaotic sequence of value sfrom [0..1K], length=200

✘

WRONG ANSWER
got 198 expected 179

▶

medium3
chaotic sequence of values from [0..10], length=200

✘

WRONG ANSWER
got 83 expected 11

▶

large1
chaotic sequence of values from [0..100K], length=10K

✘

WRONG ANSWER
got 9997 expected 9522

▶

large_random1
chaotic sequence of values from [-1M..1M], length=100K

✘

WRONG ANSWER
got 100000 expected 97534

▶

large_random2
another chaotic sequence of values from [-1M..1M], length=100K

✘

WRONG ANSWER
got 99997 expected 97527