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Distinct: Compute number of distinct values in an array.

Task description
Write a function
class Solution { public int solution(int[] A); }
that, given a zero-indexed array A consisting of N integers, returns the number of distinct values in array A.
Assume that:
  • 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].
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] = 1the function should return 3, because there are 3 distinct values appearing in array A, namely 1, 2 and 3.
Complexity:
  • expected worst-case time complexity is O(N*log(N));
  • expected worst-case space complexity is O(N), beyond input storage (not counting the storage required for input arguments).
Elements of input arrays can be modified.


class Solution { public int solution(int[] A) { // write your code in Java SE 8 int len=A.length; int count=1; int tmp=0; for(int i=0;i<len;i++){ for(int j=i+1;j<len;j++){ if(A[i]>A[j]){ tmp=A[i]; A[i]=A[j]; A[j]=tmp; } } } for(int i=0;i<len-1;i++){ if(A[i]!=A[i+1])count++; } if(len==0) count=0; return count; } }

 75%                                                       75 out of 100 points

Analysis summary
The following issues have been detected: timeout errors.
Analysis
Detected time complexity:
O(N**2)

expand allExample tests
▶
example1 
example test, positive answer
✔
OK
expand allCorrectness tests
▶
extreme_empty 
empty sequence
✔
OK
▶
extreme_single 
sequence of one element
✔
OK
▶
extreme_two_elems 
sequence of three distinct elements
✔
OK
▶
extreme_one_value 
sequence of 10 equal elements
✔
OK
▶
extreme_negative 
sequence of negative elements, length=5
✔
OK
▶
extreme_big_values 
sequence with big values, length=5
✔
OK
▶
medium1 
chaotic sequence of value sfrom [0..1K], length=100
✔
OK
▶
medium2 
chaotic sequence of value sfrom [0..1K], length=200
✔
OK
▶
medium3 
chaotic sequence of values from [0..10], length=200
✔
OK
expand allPerformance tests
▶
large1 
chaotic sequence of values from [0..100K], length=10K
✘
TIMEOUT ERROR 
running time: 2.67 sec., time limit: 2.41 sec.
▶
large_random1 
chaotic sequence of values from [-1M..1M], length=100K
✘
TIMEOUT ERROR 
running time: >9.00 sec., time limit: 3.61 sec.
▶
large_random2 
another chaotic sequence of values from [-1M..1M], length=100K
✘
TIMEOUT ERROR 
running time: >9.00 sec., time limit: 3.59 sec.

Comments

  1. Rakesh KumarNovember 16, 2018 at 6:24 PM

    I have added a code that got 100 % on codility.

    function solution($A) {
    // write your code in PHP7.0
    $A=array_unique($A);
    return count($A);
    exit(1);
    }
    https://app.codility.com/demo/results/trainingAJVQCH-PRQ/

    ReplyDelete

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