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AVAILABLE LESSONS:

Lesson 1

Iterations

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Arrays

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Time Complexity

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Counting Elements

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Prefix Sums

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Stacks and Queues

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Leader

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Maximum slice problem

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Prime and composite numbers

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Sieve of Eratosthenes

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Fibonacci numbers

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Greedy algorithms

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Dynamic programming

Lesson 90

Tasks from Indeed Prime 2015 challenge

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Tasks from Indeed Prime 2016 challenge

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Tasks from Indeed Prime 2016 College Coders challenge

Lesson 99

Future training

respectable

Count the minimum number of nails that allow a series of planks to be nailed.

Programming language:
Spoken language:

You are given two non-empty arrays A and B consisting of N integers. These arrays represent N planks. More precisely, A[K] is the start and B[K] the end of the K−th plank.

Next, you are given a non-empty array C consisting of M integers. This array represents M nails. More precisely, C[I] is the position where you can hammer in the I−th nail.

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

The goal is to find the minimum number of nails that must be used until all the planks are nailed. In other words, you should find a value J such that all planks will be nailed after using only the first J nails. More precisely, for every plank (A[K], B[K]) such that 0 ≤ K < N, there should exist a nail C[I] such that I < J and A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Thus, four is the minimum number of nails that, used sequentially, allow all the planks to be nailed.

Write a function:

int solution(int A[], int B[], int N, int C[], int M);

that, given two non-empty arrays A and B consisting of N integers and a non-empty array C consisting of M integers, returns the minimum number of nails that, used sequentially, allow all the planks to be nailed.

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

Copyright 2009–2018 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

You are given two non-empty arrays A and B consisting of N integers. These arrays represent N planks. More precisely, A[K] is the start and B[K] the end of the K−th plank.

Next, you are given a non-empty array C consisting of M integers. This array represents M nails. More precisely, C[I] is the position where you can hammer in the I−th nail.

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

The goal is to find the minimum number of nails that must be used until all the planks are nailed. In other words, you should find a value J such that all planks will be nailed after using only the first J nails. More precisely, for every plank (A[K], B[K]) such that 0 ≤ K < N, there should exist a nail C[I] such that I < J and A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Thus, four is the minimum number of nails that, used sequentially, allow all the planks to be nailed.

Write a function:

int solution(vector<int> &A, vector<int> &B, vector<int> &C);

that, given two non-empty arrays A and B consisting of N integers and a non-empty array C consisting of M integers, returns the minimum number of nails that, used sequentially, allow all the planks to be nailed.

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

Copyright 2009–2018 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

You are given two non-empty arrays A and B consisting of N integers. These arrays represent N planks. More precisely, A[K] is the start and B[K] the end of the K−th plank.

Next, you are given a non-empty array C consisting of M integers. This array represents M nails. More precisely, C[I] is the position where you can hammer in the I−th nail.

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

The goal is to find the minimum number of nails that must be used until all the planks are nailed. In other words, you should find a value J such that all planks will be nailed after using only the first J nails. More precisely, for every plank (A[K], B[K]) such that 0 ≤ K < N, there should exist a nail C[I] such that I < J and A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Thus, four is the minimum number of nails that, used sequentially, allow all the planks to be nailed.

Write a function:

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

that, given two non-empty arrays A and B consisting of N integers and a non-empty array C consisting of M integers, returns the minimum number of nails that, used sequentially, allow all the planks to be nailed.

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

Copyright 2009–2018 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

func Solution(A []int, B []int, C []int) int

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

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

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

function solution(A, B, C);

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

function solution(A, B, C)

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

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.

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

int solution(NSMutableArray *A, NSMutableArray *B, NSMutableArray *C);

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

function solution(A: array of longint; B: array of longint; N: longint; C: array of longint; M: longint): longint;

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

function solution($A, $B, $C);

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

sub solution { my ($A, $B, $C)=@_; my @A=@$A; my @B=@$B; my @C=@$C; ... }

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

def solution(A, B, C)

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

def solution(a, b, c)

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

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

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

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

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

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

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

We say that a plank (A[K], B[K]) is nailed if there exists a nail C[I] such that A[K] ≤ C[I] ≤ B[K].

For example, given arrays A, B such that:

four planks are represented: [1, 4], [4, 5], [5, 9] and [8, 10].

Given array C such that:

if we use the following nails:

- 0, then planks [1, 4] and [4, 5] will both be nailed.
- 0, 1, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, then planks [1, 4], [4, 5] and [5, 9] will be nailed.
- 0, 1, 2, 3, then all the planks will be nailed.

Write a function:

Private Function solution(A As Integer(), B As Integer(), C As Integer()) As Integer

If it is not possible to nail all the planks, the function should return −1.

For example, given arrays A, B, C such that:

the function should return 4, as explained above.

Write an ** efficient** algorithm for the following assumptions:

- N and M are integers within the range [1..30,000];
- each element of arrays A, B, C is an integer within the range [1..2*M];
- A[K] ≤ B[K].

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