public static void problem1(int num) {

int sum = 0;

for (int i = 0; i < num; i++) {

if (i % 3 == 0 || i % 5 == 0)

sum += i;

}

System.out.println("The sum of the numbers is: " + sum);

}

public static void problem2() {

int sum = 0;

int num1 = 1;

int num2 = 2;

while(num2 < 4000000) {

if (num2 % 2 == 0)

sum+= num2;

int save = num2;

num2 += num1;

num1 = save;

}

System.out.println(sum);

}

public static int problem3(long num) {

int prime = 1;

for (int i = 1; i < Math.sqrt(num); i++) {

if (num % i == 0) {

if (testPrime(i))

prime = i;

}

}

return prime;

}

public static boolean testPrime(int num) {

for (int i = 2; i <= Math.sqrt(num); i++) {

if (num % i == 0)

return false;

}

return true;

}

public static int problem4() {

int palindrome = 0;

for (int i = 999; i > 100; i--) {

for (int j = 999; j > 100; j--) {

if (palindrome(i*j)) {

if (i*j > palindrome)

palindrome = i*j;

}

}

}

return palindrome;

}

public static boolean palindrome(Integer num) {

String s = num.toString();

for (int i = 0; i < s.length()/2; i++) {

if (s.charAt(i) != s.charAt(s.length() - 1 - i))

return false;

}

return true;

}

public static int problem5() {

int i = 1;

while(true) {

if (i%20==0 && i%19==0 && i%18==0 && i%17==0 && i%16==0 && i%15==0 && i%14==0 && i%13==0 && i%12==0 && i%11==0)

return i;

i++;

}

}

public static int problem6() {

int sumOfSquares = 0;

int squareOfSum = 0;

for (int i = 1; i <= 100; i++) {

sumOfSquares += (int)Math.pow(i,2);

squareOfSum += i;

}

squareOfSum = (int)Math.pow(squareOfSum,2);

return squareOfSum - sumOfSquares;

}

public static int problem7() {

int numPrime = 0;

int i = 1;

while(numPrime<=10001) {

if (testPrime(i))

numPrime++;

i++;

}

return i;

}

public static int problem8(String num) {

int product = 0;

for (int i = 0; i < num.length() - 5; i++) {

int value = Character.getNumericValue(num.charAt(i)) * Character.getNumericValue(num.charAt(i+1)) *

Character.getNumericValue(num.charAt(i+2)) * Character.getNumericValue(num.charAt(i+3)) *

Character.getNumericValue(num.charAt(i+4));

if (value > product)

product = value;

}

return product;

}

public static int problem9() {

for (int i = 1; i < 1000; i++) {

for (int j = 1; j < 1000; j++) {

for (int k = 1; k < 1000; k++) {

if (Math.pow(i,2) + Math.pow(j,2) == Math.pow(k,2) && i + j + k == 1000) {

System.out.println(i + " " + j + " " + k);

return i*j*k;

}

}

}

}

return -1;

}

public static long problem10() {

long sum = 0;

for (int i = 2; i <= 2000000; i++) {

if (testPrime(i))

sum += i;

}

return sum;

}

public static int problem11() {

int[][] grid =

{ {8, 02, 22, 97, 38, 15, 00, 40, 00, 75, 04, 05, 07, 78, 52, 12, 50, 77, 91, 8},

{49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 00},

{81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65},

{52, 70, 95, 23, 04, 60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91},

{22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80},

{24, 47, 32, 60, 99, 03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50},

{32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70},

{67, 26, 20, 68, 02, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21},

{24, 55, 58, 05, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72},

{21, 36, 23, 9, 75, 00, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95},

{78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 9, 53, 56, 92},

{16, 39, 05, 42, 96, 35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57},

{86, 56, 00, 48, 35, 71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58},

{19, 80, 81, 68, 05, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40},

{04, 52, 8, 83, 97, 35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66},

{88, 36, 68, 87, 57, 62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69},

{04, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36},

{20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16},

{20, 73, 35, 29, 78, 31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54},

{01, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48} };

int product = 0;

for (int i = 0; i < grid.length; i++) {

for (int j = 0; j < grid[0].length; j++) {

if (i + 4 < grid.length) {

int value = grid[i][j] * grid[i+1][j] * grid[i+2][j] * grid[i+3][j];

if (value > product)

product = value;

}

if (j + 4 < grid[0].length) {

int value = grid[i][j] * grid[i][j+1] * grid[i][j+2] * grid[i][j+3];

if (value > product)

product = value;

}

if (i + 4 < grid.length && j + 4 < grid.length) {

int value = grid[i][j] * grid[i+1][j+1] * grid[i+2][j+2] * grid[i+3][j+3];

if (value > product)

product = value;

}

if (i > 2 && j < grid.length - 4) {

int value = grid[i][j] * grid[i-1][j+1] * grid[i-2][j+2] * grid[i-3][j+3];

if (value > product)

product = value;

}

}

}

return product;

}

public static int problem12() {

int triangle = 1;

int ctr = 1;

while(true) {

int divisors = 0;

for (int j = 1; j <= Math.sqrt(triangle); j++) {

if (triangle % j == 0)

divisors++;

}

divisors = divisors * 2;

if (divisors > 500)

return triangle;

ctr++;

triangle += (ctr);

}

}

public static void problem13(String numbers) {

String[] nums = new String[numbers.length() / 50];

for (int i = 0; i < (numbers.length() / 50); i++) {

StringBuilder b = new StringBuilder();

for (int j = i*50; j < i*50+50; j++) {

b.append(numbers.charAt(j));

}

nums[i] = b.toString();

System.out.println(nums[i]);

}

String[] sums = new String[nums[0].length()];

int sum = 0;

for (int i = nums[0].length() - 1; i >= 0; i--) {

for (int j = 0; j < nums.length; j++) {

sum += Character.getNumericValue(nums[j].charAt(i));

}

if (i > 0) {

sums[49-i] = "" + (sum % 10);

sum = sum / 10;

}

else

sums[49-i] = ""+sum;

}

for (int i = sums.length-1; i >= 0; i--) {

System.out.print(sums[i]);

}

}

public static int problem14() {

int longest = 0;

int num = 0;

for (int i = 2; i < 1000000; i++) {

int testSeq = collatz(i);

if (testSeq > longest) {

longest = testSeq;

num = i;

}

}

return num;

}

public static int collatz(long i) {

int seq = 1;

while (i > 1) {

if (i % 2 == 0) {

i = i/2;

seq++;

}

else {

i = (3*i)+1;

seq++;

}

}

return seq;

}

public static int problem16(String num) {

int sumOfDigits = 0;

for (int i = 0; i < num.length(); i++) {

sumOfDigits += Character.getNumericValue(num.charAt(i));

}

return sumOfDigits;

}

public static int problem17() {

String[] ones = {"","one","two","three","four","five","six","seven","eight","nine","ten"};

String[] teens = {"ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};

String[] tens = {"","ten","twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};

String[] hundreds = {"","onehundred","twohundred","threehundred","fourhundred","fivehundred","sixhundred","sevenhundred","eighthundred","ninehundred"};

StringBuilder s = new StringBuilder();

for (int i = 0; i < 1000; i++) {

if (i >= 100) {

s.append(hundreds[Character.getNumericValue((""+i).charAt(0))]);

if (Character.getNumericValue((""+i).charAt(1)) > 0 || Character.getNumericValue((""+i).charAt(2)) > 0) {

s.append("and");

if (Character.getNumericValue((""+i).charAt(1)) == 1) {

s.append(teens[Character.getNumericValue((""+i).charAt(2))]);

}

else {

s.append(tens[Character.getNumericValue((""+i).charAt(1))]);

s.append(ones[Character.getNumericValue((""+i).charAt(2))]);

}

}

}

else if (i >= 20) {

s.append(tens[Character.getNumericValue((""+i).charAt(0))]);

s.append(ones[Character.getNumericValue((""+i).charAt(1))]);

}

else if (i > 10) {

s.append(teens[Character.getNumericValue((""+i).charAt(1))]);

}

else if (i==10) {

s.append("ten");

}

else {

s.append(ones[Character.getNumericValue((""+i).charAt(0))]);

}

}

s.append("onethousand");

return s.toString().length();

}

public static int problem18() {

// String[] {"75","9564","174782","18358710","2004824765","190123750334","88027773076367","9965042806167092",

// "414126568340807033","41487233473237169429","5371446525439152975114","70 11 33 28 77 73 17 78 39 681757"}

//Unfinished

return -1;

}

public static int problem19() {

int numSundays = 0;

for (int i = 1901; i <= 2000; i++) {

for (int j = 1; j <= 12; j++) {

if (getDay(1,j,i) == 0)

numSundays++;

}

}

return numSundays;

}

public static int getDay(int day, int month, int year) {

int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};

year -= (month < 3 ? 1 : 0);

return (year + year/4 - year/100 + year/400 + t[month-1] + day) % 7;

}

public static String getDay2(int day, int month, int year) {

int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};

year -= (month < 3 ? 1 : 0);

switch ((year + year/4 - year/100 + year/400 + t[month-1] + day) % 7) {

case 0:

return "Sunday";

case 1:

return "Monday";

case 2:

return "Tuesday";

case 3:

return "Wednesday";

case 4:

return "Thursday";

case 5:

return "Friday";

case 6:

return "Saturday";

default:

return "error...";

}

}

public static int problem20() {

String num = "" + factorial(100, 200);

int sum = 0;

for (int i = 0; i < num.length(); i++) {

sum += Integer.parseInt("" + num.charAt(i));

}

return sum;

}

public static BigDecimal factorial(int x, int precision) {

MathContext mc = new MathContext(precision);

BigDecimal result = new BigDecimal(1,mc);

for (int i = x; i > 1; i--) {

result = result.multiply(new BigDecimal(i,mc));

}

return result;

}

public static int problem21() {

int sum = 0;

for (int i = 0; i <= 10000; i++) {

if (isAmicable(i)) {

sum += i;

}

}

return sum;

}

public static boolean isAmicable(int i) {

int sumFactors_i = 0;

int sumFactors_n = 0;

for (int j = 1; j < i-1; j++) {

if (i%j == 0)

sumFactors_i += j;

}

for (int j = 1; j < sumFactors_i-1; j++) {

if (sumFactors_i%j == 0)

sumFactors_n+=j;

}

return (sumFactors_n == i && i != sumFactors_i);

}

public static double problem22() {

String[] names = sortNames(getNames());

double totalScore = 0.0;

for (int i = 0; i < names.length; i++) {

int nameScore = 0;

for (int j = 0; j < names[i].length(); j++) {

nameScore += ((int)names[i].charAt(j) - 64);

}

totalScore += nameScore * (i+1);

}

return totalScore;

}

public static String[] sortNames(String[] names) {

Arrays.sort(names);

String[] sortedNames = names;

return sortedNames;

}

public static String[] getNames() {

try{

// Open the file that is the first

// command line parameter

FileInputStream fstream = new FileInputStream("names.txt");

// Get the object of DataInputStream

StringBuilder b = new StringBuilder();

DataInputStream in = new DataInputStream(fstream);

BufferedReader br = new BufferedReader(new InputStreamReader(in));

String strLine;

//Read File Line By Line

while ((strLine = br.readLine()) != null) {

b.append(strLine.trim());

}

//Close the input stream

in.close();

return b.toString().replaceAll("\"","").split(",");

}

catch (Exception e){//Catch exception if any

System.err.println("Error: " + e.getMessage());

}

return new String[] {""};

}

public static double problem23() {

int[] abundantNumbers = abundantNumbers();

double sum = 0.0;

for (int i = 0; i < 28125; i++) {

if (!sumAbundantNumbers(i,abundantNumbers))

sum+=i;

}

return sum;

}

public static boolean sumAbundantNumbers(int num, int[] abundantNumbers) {

for (int i = 0; i < abundantNumbers.length; i++) {

for (int j = 0; j < abundantNumbers.length && abundantNumbers[i] + abundantNumbers[j] <= num; j++) {

if (abundantNumbers[i] + abundantNumbers[j] == num)

return true;

}

}

return false;

}

public static int[] abundantNumbers() {

ArrayList nums = new ArrayList(100);

for (int i = 0; i < 30000; i++) {

int sumFactors = 0;

for (int j = 1; j < i; j++) {

if (i%j==0)

sumFactors += j;

}

if (sumFactors > i) {

nums.add(new Integer(i));

}

}

nums.trimToSize();

int[] abundantNumbers = new int[nums.size()];

for (int i = 0; i < nums.size(); i++) {

abundantNumbers[i] = (Integer)nums.get(i);

}

Arrays.sort(abundantNumbers);

return abundantNumbers;

}

public static String problem24() {

long startTime = Calendar.getInstance().getTimeInMillis();

ArrayList aArray = new ArrayList();

ArrayList numbers = new ArrayList(10000000);

for (int i = 0; i < 10; i++) {

aArray.add(i);

}

for (Object a : aArray) {

ArrayList bArray = new ArrayList(aArray);

bArray.remove(a);

for (Object b:bArray) {

ArrayList cArray = new ArrayList(bArray);

cArray.remove(b);

for (Object c:cArray) {

ArrayList dArray = new ArrayList(cArray);

dArray.remove(c);

for (Object d:dArray) {

ArrayList eArray = new ArrayList(dArray);

eArray.remove(d);

for (Object e:eArray) {

ArrayList fArray = new ArrayList(eArray);

fArray.remove(e);

for (Object f:fArray) {

ArrayList gArray = new ArrayList(fArray);

gArray.remove(f);

for (Object g:gArray) {

ArrayList hArray = new ArrayList(gArray);

hArray.remove(g);

for (Object h:hArray) {

ArrayList iArray = new ArrayList(hArray);

iArray.remove(h);

for (Object i:iArray) {

ArrayList jArray = new ArrayList(iArray);

jArray.remove(i);

for (Object j:jArray) {

String num = "" + a + b + c + d + e + f + g + h + i + j;

numbers.add(num);

if (numbers.size() == 1000000) {

long endTime = Calendar.getInstance().getTimeInMillis();

System.out.println("That took: " + (endTime - startTime) + " milliseconds.");

return numbers.get(999999).toString();

}

}

}

}

}

}

}

}

}

}

}

return "error";

}