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AVAILABLE LESSONS:

Lesson 1

Iterations

Lesson 2

Arrays

Lesson 3

Time Complexity

Lesson 4

Counting Elements

Lesson 5

Prefix Sums

Lesson 6

Sorting

Lesson 7

Stacks and Queues

Lesson 8

Leader

Lesson 9

Maximum slice problem

Lesson 10

Prime and composite numbers

Lesson 11

Sieve of Eratosthenes

Lesson 12

Euclidean algorithm

Lesson 13

Fibonacci numbers

Lesson 14

Binary search algorithm

Lesson 15

Caterpillar method

Lesson 16

Greedy algorithms

Lesson 17

Dynamic programming

Lesson 99

Future training

Compute number of inversion in an array.

Spoken language:

An array A consisting of N integers is given. An *inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

int solution(int A[], int N);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

Copyright 2009–2023 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

An array A consisting of N integers is given. An *inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

int solution(vector<int> &A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

Copyright 2009–2023 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

An array A consisting of N integers is given. An *inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

int solution(vector<int> &A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

Copyright 2009–2023 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

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

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

int solution(List<int> A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

func Solution(A []int) int

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

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

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

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

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

function solution(A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

fun solution(A: IntArray): Int

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

function solution(A)

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

Note: All arrays in this task are zero-indexed, unlike the common Lua convention. You can use `#A` to get the length of the array A.

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

int solution(NSMutableArray *A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

function solution(A: array of longint; N: longint): longint;

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

function solution($A);

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

sub solution { my (@A) = @_; ... }

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

def solution(A)

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

def solution(a)

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

object Solution { def solution(a: Array[Int]): Int }

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

public func solution(_ A : inout [Int]) -> Int

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

function solution(A: number[]): number;

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].

*inversion* is a pair of indexes (P, Q) such that P < Q and A[Q] < A[P].

Write a function:

Private Function solution(A As Integer()) As Integer

that computes the number of inversions in A, or returns −1 if it exceeds 1,000,000,000.

For example, in the following array:

there are four inversions:

so the function should return 4.

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 [−2,147,483,648..2,147,483,647].