Test results - Codility

Tasks Details

easy

1. Distinct

Compute number of distinct values in an array.

100%

Write a function

class Solution { public int solution(int[] 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 Java 8

Time spent on task 7 minutes

Notes

not defined yet

Task timeline

Code: 23:19:10 UTC, java, verify, result: Passed

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

// 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");
import java.util.HashSet;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        HashSet hs = new HashSet();
        for(int i=0; i<A.length;i++) {
            hs.add(A[i]);
        }
        return hs.size();
    }
}

Analysis

▶

example1
example test, positive answer

✔

Code: 23:19:24 UTC, java, verify, result: Passed

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

// 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");
import java.util.HashSet;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        HashSet hs = new HashSet();
        for(int i=0; i<A.length;i++) {
            hs.add(A[i]);
        }
        return hs.size();
    }
}

Analysis

▶

example1
example test, positive answer

✔

Code: 23:19:32 UTC, java, final, score: 100

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

// 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");
import java.util.HashSet;
class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        HashSet hs = new HashSet();
        for(int i=0; i<A.length;i++) {
            hs.add(A[i]);
        }
        return hs.size();
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N*log(N)) or O(N)

▶

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

✔

▶

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

✔

▶

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

✔

▶

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

✔

▶

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

✔

▶

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

✔