[Hacker Rank] Warm up: Time Conversion solved ✓

algorithm-exercises-java/src/main/java/ae/hackerrank/warmup/TimeConversion.java

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+package ae.hackerrank.warmup;
+
+import org.checkerframework.common.value.qual.StringVal;
+
+/**
+ * Time Conversion.
+ *
+ * @link Problem definition [[docs/hackerrank/warmup/solve_me_first.md]]
+ */
+public class TimeConversion {
+
+  private TimeConversion() {
+  }
+
+  static java.util.logging.Logger logger = util.CustomLogger.getLogger();
+
+  /**
+   * timeConversion.
+   */
+  public static String timeConversion(String input) {
+    String meridian = input.substring(input.length() - 2);
+    meridian = meridian.toLowerCase();
+
+    String timeStr = input.substring(0, input.length() - 2);
+    String[] time = timeStr.split(":");
+
+    int hour = Integer.parseInt(time[0]);
+
+    if (hour >= 12)  {
+      hour = 0;
+    }
+    if (meridian.equals("pm")) {
+      hour += 12;
+    }
+
+    time[0] = String.format("%02d", hour);
+
+    return String.join(":", time);
+  }
+}

algorithm-exercises-java/src/test/java/ae/hackerrank/warmup/TimeConversionTest.java

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+package ae.hackerrank.warmup;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.TestInstance.Lifecycle;
+
+@TestInstance(Lifecycle.PER_CLASS)
+class TimeConversionTest {
+  public class TimeConversionTestCase {
+    public String input;
+    public String expected;
+
+    public TimeConversionTestCase(String _input, String _expected) {
+      this.input = _input;
+      this.expected = _expected;
+    }
+  }
+
+  public List<TimeConversionTestCase> testCases;
+
+  @BeforeAll
+  public void setup() {
+    this.testCases = Arrays.asList(
+      new TimeConversionTestCase("12:01:00PM", "12:01:00"),
+      new TimeConversionTestCase("12:01:00AM", "00:01:00")
+    );
+  }
+
+  @Test
+  void testStaircase() {
+    for (TimeConversionTestCase testCase : this.testCases) {
+      String solutionFound = TimeConversion.timeConversion(testCase.input);
+
+      assertEquals(testCase.expected, solutionFound,
+          String.format("%s(%s) answer must be: %s",
+              "Staircase.staircase",
+              testCase.input,
+              testCase.expected));
+    }
+  }
+}

docs/hackerrank/warmup/time_conversion.md

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+# [Time Conversion](https://www.hackerrank.com/challenges/time-conversion)
+
+Difficulty: #easy
+Category: #warmup
+
+Given a time in
+12-[hour AM/PM format](https://en.wikipedia.org/wiki/12-hour_clock),
+convert it to military (24-hour) time.
+
+Note:
+
+- 12:00:00AM on a 12-hour clock is 00:00:00 on a 24-hour clock.
+- 12:00:00PM on a 12-hour clock is 12:00:00 on a 24-hour clock.
+
+## Example
+
+- s = '12:01:00PM' \
+  Return '12:01:00'
+- s = '12:01:00AM' \
+  Return '00:01:00'
+
+## Function Description
+
+Complete the timeConversion function in the editor below.
+It should return a new string representing the input time in 24 hour format
+timeConversion has the following parameter(s):
+
+- string s: a time in 12 hour format
+
+## Returns
+
+- string: the time in 24 hour format
+
+## Input Format
+
+A single string s that represents a time in 12-hour clock format
+(i.e.: hh_mm_ssAM or hh:mm:ssPM).
+
+## Constraints
+
+- All input times are valid
+
+## Sample Input 0
+
+```text
+07:05:45PM
+```
+
+## Sample Output 0
+
+```text
+19:05:45
+```