Graduate Software Engineer Interview Questions

import java.util.ArrayList; public class TestRun2 { public static void main(String[] args) { /* * Write a function that when given a string will return the position of * the starting point of the largest reoccurring character. (ie. * given:"AAABBCCCCD" would return 5 (starting point of C)) */ String input = "AAABBCCCCD"; System.out.print(largestReoccuringCharacter(input)); } public static int largestReoccuringCharacter(String input) { // 1. Count all the characters, find the character that reoccurs the // most // 2. Find the position of the first most reoccuring character if(input == null || input.isEmpty()) { return -1; } ArrayList charArrayList = new ArrayList(); ArrayList charIndexList = new ArrayList(); // Add all elements in input to ArrayList, and also a HashSet for (char c : input.toCharArray()) { Character inChar = (Character) c; // convert to object charArrayList.add(inChar); if (!charIndexList.contains(inChar)) { charIndexList.add(inChar); } } // For each char in the index, count occurences in arraylist. Find most // occuring int highestNumberOfOccurences = -1; Character highestChar = null; for (Character c : charIndexList) { int count = 0; while (charArrayList.contains(c)) { charArrayList.remove(c); count++; } if (count > highestNumberOfOccurences) { highestNumberOfOccurences = count; highestChar = c; } } // found character with highest count. Return index position. return input.indexOf(highestChar.toString()); } } JUnit Test: import static org.junit.Assert.*; import org.junit.Test; public class TestRun2Test { @Test public void testLargestReoccuringCharacter() { String input1 = "AAABBCCCCD"; String input2 = "AAABBCCCCDDDDD"; String input3 = "AAABBCCCCDDDD"; String input4 = "AAABBCCCC AADDDD"; String input5 = " "; String input6 = ""; String input7 = null; assertEquals(TestRun2.largestReoccuringCharacter(input1), 5); assertEquals(TestRun2.largestReoccuringCharacter(input2), 9); assertEquals(TestRun2.largestReoccuringCharacter(input3), 5); assertEquals(TestRun2.largestReoccuringCharacter(input4), 0); assertEquals(TestRun2.largestReoccuringCharacter(input5), 0); assertEquals(TestRun2.largestReoccuringCharacter(input6), -1); assertEquals(TestRun2.largestReoccuringCharacter(input7), -1); } }