Test results - Codility

Tasks Details

easy

1. FrogJmp

Count minimal number of jumps from position X to Y.

100%

Task description

A small frog wants to get to the other side of the road. The frog is currently located at position X and wants to get to a position greater than or equal to Y. The small frog always jumps a fixed distance, D.

Count the minimal number of jumps that the small frog must perform to reach its target.

Write a function:

object Solution { def solution(x: Int, y: Int, d: Int): Int }

that, given three integers X, Y and D, returns the minimal number of jumps from position X to a position equal to or greater than Y.

For example, given:

X = 10 Y = 85 D = 30

the function should return 3, because the frog will be positioned as follows:

after the first jump, at position 10 + 30 = 40

after the second jump, at position 10 + 30 + 30 = 70

after the third jump, at position 10 + 30 + 30 + 30 = 100

Write an efficient algorithm for the following assumptions:

X, Y and D are integers within the range [1..1,000,000,000];

X ≤ Y.

Solution

Programming language used Scala

Time spent on task 4 minutes

Notes

not defined yet

Task timeline

00:10:43

00:13:48

Away from Codility tab

Code: 00:13:48 UTC, scala, final, score: 100

1 2 3 4 5 6 7 8 9 10

import scala.collection.JavaConversions._

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

object Solution {
    def solution(X: Int, Y: Int, D: Int): Int = {
        math.ceil((Y - X).toDouble / D).toInt
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(1)

▶

example
example test

✔

▶

simple1
simple test

✔

▶

simple2

✔

▶

extreme_position
no jump needed

✔

▶

small_extreme_jump
one big jump

✔

▶

many_jump1
many jumps, D = 2

✔

▶

many_jump2
many jumps, D = 99

✔

▶

many_jump3
many jumps, D = 1283

✔

▶

big_extreme_jump
maximal number of jumps

✔

▶

small_jumps
many small jumps

✔

Code: 00:11:00 UTC, scala, verify, result: Failed

1 2 3 4 5 6 7 8 9 10

import scala.collection.JavaConversions._

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

object Solution {
    def solution(X: Int, Y: Int, D: Int): Int = {
        (Y - X) / D
    }
}

Analysis

▶

example
example test

✘

WRONG ANSWER
got 2 expected 3

Code: 00:11:22 UTC, scala, verify, result: Failed

1 2 3 4 5 6 7 8 9 10

import scala.collection.JavaConversions._

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

object Solution {
    def solution(X: Int, Y: Int, D: Int): Int = {
        math.ceil((Y - X) / D).toInt
    }
}

Analysis

▶

example
example test

✘

WRONG ANSWER
got 2 expected 3

Code: 00:13:48 UTC, scala, final, score: 100

1 2 3 4 5 6 7 8 9 10

import scala.collection.JavaConversions._

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

object Solution {
    def solution(X: Int, Y: Int, D: Int): Int = {
        math.ceil((Y - X).toDouble / D).toInt
    }
}

Analysis summary

The solution obtained perfect score.

Analysis

Detected time complexity:

O(1)

▶

example
example test

✔

▶

simple1
simple test

✔

▶

simple2

✔

▶

extreme_position
no jump needed

✔

▶

small_extreme_jump
one big jump

✔

▶

many_jump1
many jumps, D = 2

✔

▶

many_jump2
many jumps, D = 99

✔

▶

many_jump3
many jumps, D = 1283

✔

▶

big_extreme_jump
maximal number of jumps

✔

▶

small_jumps
many small jumps

✔