Test results - Codility

Tasks Details

easy

1. PermMissingElem

Find the missing element in a given permutation.

100%

An array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.

Your goal is to find that missing element.

Write a function:

class Solution { public int solution(int[] A); }

that, given an array A, returns the value of the missing element.

For example, given array A such that:

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

the function should return 4, as it is the missing element.

Write an efficient algorithm for the following assumptions:

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

the elements of A are all distinct;

each element of array A is an integer within the range [1..(N + 1)].

Solution

Programming language used Java 8

Time spent on task 1 minutes

Notes

not defined yet

Task timeline

Code: 04:27:10 UTC, java, verify, result: Passed

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// you can also use imports, for example:
import java.util.Arrays;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        if(A.length == 0) return 1;
    	
        Arrays.sort(A);

        for(int i=0; i<A.length; i++){
            if( A[i] != i+1 ){
                return i+1;
            }
        }

        return A[A.length-1]+1;
    }
}

Analysis

▶

example
example test

✔

Code: 04:27:16 UTC, java, final, score: 100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

// you can also use imports, for example:
import java.util.Arrays;

// you can write to stdout for debugging purposes, e.g.
// System.out.println("this is a debug message");

class Solution {
    public int solution(int[] A) {
        // write your code in Java SE 8
        if(A.length == 0) return 1;
    	
        Arrays.sort(A);

        for(int i=0; i<A.length; i++){
            if( A[i] != i+1 ){
                return i+1;
            }
        }

        return A[A.length-1]+1;
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

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

▶

example
example test

✔

▶

empty_and_single
empty list and single element

✔

▶

missing_first_or_last
the first or the last element is missing

✔

▶

single
single element

✔

▶

double
two elements

✔

▶

simple
simple test

✔

▶

medium1
medium test, length = ~10,000

✔

▶

medium2
medium test, length = ~10,000

✔

▶

large_range
range sequence, length = ~100,000

✔

▶

large1
large test, length = ~100,000

✔

▶

large2
large test, length = ~100,000

✔