InterviewStuff.java

package PortfolioTests;

import java.util.Arrays;

public class CodeWars {
    public static void main(String[] args) {
        Integer[] ar = {100, 5, 3, 99, 34, 63, 2};
        int sum = 39;
//        bubble(ar);
//        findSum(ar, sum);
        System.out.println(findSum(ar, sum));
    }

    public static void fib() {
        for(int i=0;i<=30;i++){
            System.out.print(fibbonaciIterative(i)+" ");
        }

        System.out.println();

        for(int i=0;i<=30;i++){
            System.out.print(fibbonaciRecursive(i)+" ");
        }
    }
    static int fibbonaciIterative(int n) {
        int a = 0, b = 1, c;
        if (n == 0)
            return a;
        for (int i = 2; i <= n; i++)
        {
            c = a + b;
            a = b;
            b = c;
        }
        return b;
    }
    static int fibbonaciRecursive(int n) {
//        if (n <= 1)
//            return n;
//        return fibbonaciRecursive(n-1) + fibbonaciRecursive(n-2);
        return (n <= 1 ? n : fibbonaciRecursive(n-1) + fibbonaciRecursive(n-2));
    }

    static void isPrime(int num) {
        if (num <= 1) {
            System.out.println(num + " is not prime");
        } else {
            boolean prime = true;
            for (int i = 2; i*i <= num; i++) {
                if (num % i == 0) {
                    prime = false;
                }
            }
            if (prime) {
                System.out.println(num + " is prime");
            } else {
                System.out.println(num + " is not prime");
            }
        }
    }

    static void isIntPalindrome(int num) {
        int revNum = 0;
        int workingNum = num;
        while (num > 0) {
            revNum = revNum * 10 + num % 10;
            num = num / 10;
        }
        if (workingNum == revNum) {
            System.out.println(workingNum + " is palindrome");
        } else {
            System.out.println(workingNum + " is not palindrome");
        }
    }

    static void isStringPalindrome(String s) {
        String tempS = s;
        String newS = "";
//        StringBuffer sb = new StringBuffer(tempS);
//        newS = sb.reverse().toString();

        //or if they're cheeky
        for (int i = s.length() - 1; i >= 0; i--) {
            newS = newS + tempS.charAt(i);
        }

        if (s.equalsIgnoreCase(newS)) {
            System.out.println(s + " is palindrome");
        } else {
            System.out.println(s + " is not palindrome");
        }
    }

    static long factorial(int num) {
        //use long but be careful as with 20! you exceed long range
        //fancy ternary operator
        return (num <= 1) ? 1 : num * factorial(num - 1);

//        if (num <= 1) {
//            return 1;
//        } else {
//            return num * factorial(num -1);
//        }

        // for loop
//        int fact = 1;
//        for (int i = 1; i <= num; i++) {
//            fact = fact * i;
//        }
//        System.out.println(fact);
    }

    static int[] bubble(int[] arr) {

        int temp;

        for (int i = 0; i < arr.length; i++) {
            for (int j = 1; j < (arr.length - i); j++) {
                if (arr[j - 1] > arr[j]) {
                    temp = arr[j - 1];
                    arr[j - 1] = arr[j];
                    arr[j] = temp;
                }
                System.out.println("Iteration " + i + " " + Arrays.toString(arr));
            }
        }

        return arr;
    }

    static String findSum(Integer[] arr, int sum) {
//        brute force
        for (int i = 0; i < arr.length; i++) {
            for (int j = 1; j < arr.length; j++) {
                if (arr[i]+arr[j] == sum) {
                    String found = "Found " + arr[i]+ " " + arr[j];
                    System.out.println(found);
//                    return found;
                }
            }
        }

        for (int i = 0; i < arr.length; i++) {
            int rezultat = sum - arr[i];
            if (Arrays.asList(arr).contains(rezultat)) {
                String found = "Gasit de data asta: " + arr[i] + " " + rezultat;
                return found;
            }
        }
        return "";
    }
}