HackerRank 30 Days Of Code Challenge, Day27(Ques 28 in Java)
This problem is about unit testing.
Your company needs a function that meets the following requirements:
- For a given array of integers, the function returns the index of the element with the minimum value in the array. If there is more than one element with the minimum value, it returns the smallest one.
- If an empty array is passed to the function, it raises an exception. A colleague has written this method. The implementation in Python is listed below. Implementations in other languages can be found in the code template.
def minimum_index(seq):
if len(seq) == 0:
raise ValueError("Cannot get the minimum value index from an empty sequence")
min_idx = 0
for i in range(1, len(seq)):
if a[i] < a[min_idx]:
min_idx = i
return min_idx
A coworker has prepared functions that will perform the tests and validate return values. Finish the implementation of classes to provide data and expected results for the tests.
Complete the following methods.
In the class TestDataEmptyArray:
get_array()returns an empty array
In the class TestDataUniqueValues:
get_array()returns an array of size at least 2 with all unique elementsget_expected_result()returns the expected minimum value index for this array
In the class TestDataExactlyTwoDifferentMinimums:
get_array()returns an array where the minimum value occurs at exactly 2 indicesget_expected_result()returns the expected index
Take a look at the code template to see the exact implementation of functions that your colleague already implemented.
Note: The arrays are indexed from .
Answer:
import java.util.*;
public class Solution {
public static int minimum_index(int[] seq) {
if (seq.length == 0) {
throw new IllegalArgumentException("Cannot get the minimum value index from an empty sequence");
}
int min_idx = 0;
for (int i = 1; i < seq.length; ++i) {
if (seq[i] < seq[min_idx]) {
min_idx = i;
}
}
return min_idx;
}
static class TestDataEmptyArray {
public static int[] get_array() {
return new int[]{};
}
}
static class TestDataUniqueValues {
public static int[] get_array() {
return new int[]{1, 2, 3, 4, 5};
}
public static int get_expected_result() {
return minimum_index(get_array());
}
}
static class TestDataExactlyTwoDifferentMinimums {
public static int[] get_array() {
return new int[] {1, 2, 3, 4, 3, 2, 1};
}
public static int get_expected_result() {
return minimum_index(get_array());
}
}
public static void TestWithEmptyArray() {
try {
int[] seq = TestDataEmptyArray.get_array();
int result = minimum_index(seq);
} catch (IllegalArgumentException e) {
return;
}
throw new AssertionError("Exception wasn't thrown as expected");
}
public static void TestWithUniqueValues() {
int[] seq = TestDataUniqueValues.get_array();
if (seq.length < 2) {
throw new AssertionError("less than 2 elements in the array");
}
Integer[] tmp = new Integer[seq.length];
for (int i = 0; i < seq.length; ++i) {
tmp[i] = Integer.valueOf(seq[i]);
}
if (!((new LinkedHashSet<Integer>(Arrays.asList(tmp))).size() == seq.length)) {
throw new AssertionError("not all values are unique");
}
int expected_result = TestDataUniqueValues.get_expected_result();
int result = minimum_index(seq);
if (result != expected_result) {
throw new AssertionError("result is different than the expected result");
}
}
public static void TestWithExactlyTwoDifferentMinimums() {
int[] seq = TestDataExactlyTwoDifferentMinimums.get_array();
if (seq.length < 2) {
throw new AssertionError("less than 2 elements in the array");
}
int[] tmp = seq.clone();
Arrays.sort(tmp);
if (!(tmp[0] == tmp[1] && (tmp.length == 2 || tmp[1] < tmp[2]))) {
throw new AssertionError("there are not exactly two minimums in the array");
}
int expected_result = TestDataExactlyTwoDifferentMinimums.get_expected_result();
int result = minimum_index(seq);
if (result != expected_result) {
throw new AssertionError("result is different than the expected result");
}
}
public static void main(String[] args) {
TestWithEmptyArray();
TestWithUniqueValues();
TestWithExactlyTwoDifferentMinimums();
System.out.println("OK");
}
}
Now just submit the code and check the result.
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