Test results - Codility

Tasks Details

medium

1. MaxCounters

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

Task Score

100%

Correctness

100%

Performance

100%

You are given N counters, initially set to 0, and you have two possible operations on them:

increase(X) − counter X is increased by 1,

max counter − all counters are set to the maximum value of any counter.

A non-empty array A of M integers is given. This array represents consecutive operations:

if A[K] = X, such that 1 ≤ X ≤ N, then operation K is increase(X),

if A[K] = N + 1 then operation K is max counter.

For example, given integer N = 5 and array A such that:

A[0] = 3 A[1] = 4 A[2] = 4 A[3] = 6 A[4] = 1 A[5] = 4 A[6] = 4

the values of the counters after each consecutive operation will be:

(0, 0, 1, 0, 0) (0, 0, 1, 1, 0) (0, 0, 1, 2, 0) (2, 2, 2, 2, 2) (3, 2, 2, 2, 2) (3, 2, 2, 3, 2) (3, 2, 2, 4, 2)

The goal is to calculate the value of every counter after all operations.

Write a function:

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

that, given an integer N and a non-empty array A consisting of M integers, returns a sequence of integers representing the values of the counters.

Result array should be returned as an array of integers.

For example, given:

A[0] = 3 A[1] = 4 A[2] = 4 A[3] = 6 A[4] = 1 A[5] = 4 A[6] = 4

the function should return [3, 2, 2, 4, 2], as explained above.

Write an efficient algorithm for the following assumptions:

N and M are integers within the range [1..100,000];

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

Solution

Programming language used Scala

Time spent on task 15 minutes

Notes

not defined yet

Task timeline

Code: 18:20:42 UTC, scala, verify, result: Failed

show code in pop-up

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

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], floor: Int): Array[Int] = {
            if (index >= A.length) {
                Array.fill(0)(N)
            } else {
                loop(index = 1, counters, foor)
            }
        }
        
        loop(0, Map.empty, 0)
    }
}

Analysis

Compile error

Solution.scala:13: error: not found: value foor
                loop(index = 1, counters, foor)
                                          ^
one error found

Code: 18:20:55 UTC, scala, verify, result: Failed

show code in pop-up

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

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], floor: Int): Array[Int] = {
            if (index >= A.length) {
                Array.fill(0)(N)
            } else {
                loop(index = 1, counters, floor)
            }
        }
        
        loop(0, Map.empty, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✘

TIMEOUT ERROR
running time: >5.00 sec., time limit: 5.00 sec.

5.000 s

TIMEOUT ERROR, running time: >5.00 sec., time limit: 5.00 sec.

Code: 18:22:16 UTC, scala, verify, result: Failed

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

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                Array.fill(0)(N)
            } else {
                loop(index + 1, counters, curMax, floor)
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got [] expected [3, 2, 2, 4, 2]

2.484 s

WRONG ANSWER, got [] expected [3, 2, 2, 4, 2]

Code: 18:23:37 UTC, scala, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(0)(N)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                loop(index + 1, counters, curMax, floor)
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✘

RUNTIME ERROR
tested program terminated unexpectedly

1.848 s

RUNTIME ERROR, tested program terminated unexpectedly

stderr:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
	at Solution$$anonfun$loop$1$1.apply$mcVI$sp(Solution.scala:14)
	at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:166)
	at Solution$.loop$1(Solution.scala:12)
	at Solution$.solution(Solution.scala:22)
	at Wrapper$.run(user.scala:32)
	at Wrapper$.main(user.scala:25)
	at Wrapper.main(user.scala)

Code: 18:25:28 UTC, scala, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                loop(index + 1, counters, curMax, floor)
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got [0, 0, 0, 0, 0] expected [3, 2, 2, 4, 2]

2.291 s

WRONG ANSWER, got [0, 0, 0, 0, 0] expected [3, 2, 2, 4, 2]

Code: 18:27:31 UTC, scala, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                val currentValue = A(i)
                if (currentValue >= 1 && currentValue < (N + 1)) {
                    println("Increment: " + currentValue)
                } else if (currentValue == (N + 1)) {
                    println("Bump all!")
                } else {
                    sys.error("Unexpected input")
                }
                loop(index + 1, counters, curMax, floor)
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

Compile error

Solution.scala:18: error: not found: value i
                val currentValue = A(i)
                                     ^
one error found

Code: 18:27:45 UTC, scala, verify, result: Failed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                val currentValue = A(index)
                if (currentValue >= 1 && currentValue < (N + 1)) {
                    println("Increment: " + currentValue)
                } else if (currentValue == (N + 1)) {
                    println("Bump all!")
                } else {
                    sys.error("Unexpected input")
                }
                loop(index + 1, counters, curMax, floor)
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✘

WRONG ANSWER
got [0, 0, 0, 0, 0] expected [3, 2, 2, 4, 2]

2.320 s

WRONG ANSWER, got [0, 0, 0, 0, 0] expected [3, 2, 2, 4, 2]

stdout:

Increment: 3
Increment: 4
Increment: 4
Bump all!
Increment: 1
Increment: 4
Increment: 4

Code: 18:30:04 UTC, scala, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                val currentValue = A(index)
                if (currentValue >= 1 && currentValue < (N + 1)) {
                    val nextCounterValue = counters.getOrElse(currentValue, 0) + 1
                    val nextMax = curMax max nextCounterValue
                    val nextCounters = counters + (currentValue -> nextCounterValue)
                    loop(index + 1, nextCounters, nextMax, floor)
                } else if (currentValue == (N + 1)) {
                    val nextFloor = floor + curMax
                    loop(index + 1, Map.empty, 0, nextFloor)
                } else {
                    sys.error("Unexpected input")
                }
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✔

2.387 s

Code: 18:30:27 UTC, scala, verify, result: Passed

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                val currentValue = A(index)
                if (currentValue >= 1 && currentValue < (N + 1)) {
                    val nextCounterValue = counters.getOrElse(currentValue, 0) + 1
                    val nextMax = curMax max nextCounterValue
                    val nextCounters = counters + (currentValue -> nextCounterValue)
                    loop(index + 1, nextCounters, nextMax, floor)
                } else if (currentValue == (N + 1)) {
                    val nextFloor = floor + curMax
                    loop(index + 1, Map.empty, 0, nextFloor)
                } else {
                    sys.error("Unexpected input")
                }
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis

expand all Example tests

▶

example
example test

✔

2.417 s

Code: 18:30:39 UTC, scala, final, score: 100

show code in pop-up

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

import scala.collection.JavaConversions._

// you can use println for debugging purposes, e.g.
// println("this is a debug message")

object Solution {
    def solution(N: Int, A: Array[Int]): Array[Int] = {
        @scala.annotation.tailrec
        def loop(index: Int, counters: Map[Int, Int], curMax: Int, floor: Int): Array[Int] = {
            if (index >= A.length) {
                val result = Array.fill(N)(0)
                (1 to N) foreach { counter =>
                    val counterValue = counters.getOrElse(counter, 0) + floor
                    result(counter - 1) = counterValue
                }
                result
            } else {
                val currentValue = A(index)
                if (currentValue >= 1 && currentValue < (N + 1)) {
                    val nextCounterValue = counters.getOrElse(currentValue, 0) + 1
                    val nextMax = curMax max nextCounterValue
                    val nextCounters = counters + (currentValue -> nextCounterValue)
                    loop(index + 1, nextCounters, nextMax, floor)
                } else if (currentValue == (N + 1)) {
                    val nextFloor = floor + curMax
                    loop(index + 1, Map.empty, 0, nextFloor)
                } else {
                    sys.error("Unexpected input")
                }
            }
        }
        
        loop(0, Map.empty, 0, 0)
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(N + M)

expand all Example tests

▶

example
example test

✔

2.408 s

expand all Correctness tests

▶

extreme_small
all max_counter operations

✔

2.307 s

▶

single
only one counter

✔

2.388 s

2.427 s

▶

small_random1
small random test, 6 max_counter operations

✔

2.597 s

▶

small_random2
small random test, 10 max_counter operations

✔

2.579 s

expand all Performance tests

▶

medium_random1
medium random test, 50 max_counter operations

✔

2.634 s

▶

medium_random2
medium random test, 500 max_counter operations

✔

2.628 s

▶

large_random1
large random test, 2120 max_counter operations

✔

3.508 s

▶

large_random2
large random test, 10000 max_counter operations

✔

3.612 s

▶

extreme_large
all max_counter operations

✔

2.965 s

2.807 s