My solutions to Codility's online lessons' tasks

All tasks and solutions will be sorted into the appropriate lessons, exactly like how codility organizes them.

Link to Lessons and tasks: https://codility.com/programmers/lessons/

Lesson 1: Iterations

BinaryGap

• Find longest sequence of zeros in binary representation of an integer.

Lesson 2: Arrays

CyclicRotation

• Rotate an array to the right by a given number of steps.

OddOccurrencesInArray

• Find value that occurs in odd number of elements.

Lesson 3: Time Complexity

TapeEquilibrium

• Minimize the value |(A[0] + ... + A[P-1]) - (A[P] + ... + A[N-1])|.

FrogJmp

• Count minimal number of jumps from position X to Y.

PermMissingElem

• Find the missing element in a given permutation.

Lesson 4: Counting Elements

FrogRiverOne

• Find the earliest time when a frog can jump to the other side of a river.

PermCheck

• Check whether array A is a permutation.

MissingInteger

• Find the minimal positive integer not occuring in a given sequence.

MaxCounters

• Calculate the values of counters after applying all alternating operations: increase counter by 1; set value of all counters to current maximum.

Lesson 5: Prefix Sums

CountDiv

• Compute number of integers divisible by k in range [a..b].

PassingCars

• Count the number of passing cars on the road.

MinAvgTwoSlice

• Find the minimal average of any slice containing at least two elements.

GenomicRangeQuery

• Find the minimal nucleotide from a range of sequence DNA.

Lesson 6: Sorting

MaxProductOfThree

• Maximize A[P]*A[Q]*A[R] for any triplet (P, Q, R).

Triangle

• Determine whether a triangle can be built from a given set of edges.

Distinct

• Compute number of distinct values in an array.

NumberOfDiscIntersections

• Compute the number of intersections in a sequence of discs.

Lesson 7: Stacks and Queues

Nesting

• Determine whether given string of parentheses is properly nested.

StoneWall

• Cover "Manhattan skyline" using the minimum number of rectangles.

Brackets

• Determine whether given string of parentheses is properly nested.

Fish

• N voracious fish are moving along a river. Calculate how many fish are still alive.

Lesson 8: Leader

Dominator

• Find an index of an array such that its value occurs at more than half of indices in the array.

EquiLeader

• Find the index S such that the leaders of the sequences A[0], A[1], ..., A[S] and A[S + 1], A[S + 2], ..., A[N - 1] are the same.

Lesson 9: Maximum Slice Problem

MaxDoubleSliceSum

• Find the maximal sum of any double slice.

MaxProfit

• Given a log of stock prices compute the maximum possible earning.

MaxSliceSum

• Find a maximum sum of a compact subsequence of array elements.

Lesson 10: Prime and Composite Numbers

MinPerimeterRectangle

• Find the minimal perimeter of any rectangle whose area equals N.

CountFactors

• Count factors of a give number n.

Peaks

• Divide an array into the maximum number of same-sized blocks, each of which should contain an index P such that A[P - 1] < A[P] > A[P + 1].

Flags

• Find the maximum number of flags that can be set on mountain peaks.

Lesson 11: Sieve of Eratosthenes

CountSemiprimes

• Count the semiprime numbers in the given range [a..b].

CountNonDivisible

• Calculate the number of elements of an array that are not divisors of each element.

Lesson 12: Euclidean algorithm

ChocolatesByNumbers

• There are N chocolates in a circle. Count the number of chocolates you will eat.

CommonPrimeDivisors

• Check whether two numbers have the same prime divisors.