soltrinox

NSArray *sortedArray;
sortedArray = [drinkDetails sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
    NSDate *first = [(Person*)a birthDate];
    NSDate *second = [(Person*)b birthDate];
    return [first compare:second];
}];

soltrinox

public static int increasingSubsequence(int[]seq){
    int[]L=new int[seq.length];
    L[0]=1;
    for(int i=1;i<L.length;i++){
      int maxn=0;
      for(int j=0;j<i;j++){
        if(seq[j]<seq[i]&&L[j]>maxn){
          maxn=L[j];
        }
      }

soltrinox

public static int binarySearch(int[]array,int key){ //looks for the index of the element that has value key, returns index. array must be sorted 
    int min=0; //initializes min, max, guess
    int max=array.length-1;
    int guess=(min+max)/2;
    while(array[guess]!=key){ //keeps on looking until key is found
      if(min==guess||max==guess){//if min=guess, max=guess, the key does not exist in the array
        return(-1);//returns -1 if key is not found
      }
      if(array[guess]>key){//you only have to search between min and guess
        max=guess;

soltrinox

public static String primeFactorization(long num){ //method signature. takes long, returns string of factorization
    String ans=""; //creates the answer
    for(int i=2;i<=num;i++){ //loops from 2 to the num
      if(num%i==0){ //checks if i is a divisor of num
        ans+=i+"*"; //writes i in prime factorization
        num=num/i; //since it is written down, num=num/i
        i--; //just in case their are multiple factors of same number. For example, 12=2*2*3
      }
    }
    return(ans.substring(0,ans.length()-1)); //takes away last asterisk. Factorization of 4=2*2*=>2*2

soltrinox

public static int[] gnomeSort(int[] nums){ //takes unsorted array, returns sorted
    int index=1; //start of search
    int temp;
    while(index<nums.length){ //until the array is fully sorted
      if(nums[index]<nums[index-1]){ //compares nums[index] with nums[index-1]. if smaller, switch.
        temp=nums[index];
        nums[index]=nums[index-1];
        nums[index-1]=temp;
        index--; //must decrease index to recheck. since they have been swapped, the array may still be out of order
        if(index==0){ //prevents index from going lower than 1

soltrinox

public static int GCD(int a, int b){ //method signature. Takes two values and returns the GCD.
    int temp;  
    if(a==b){ //Euclidean algorithm implementation. Recursion stopping case.
      return(a);
    }
    if(a<b){ //Recursion. if a<b; switch to make a>b
      temp=a;
      a=b;
      b=temp;
    }

soltrinox

public static int totient(int num){ //euler's totient function calculator. returns totient
    int count=0;
    for(int a=1;a<num;a++){ //definition of totient: the amount of numbers less than num coprime to it
      if(GCD(num,a)==1){ //coprime
        count++;
      }
    }
    return(count);
 }
public static int GCD(int a, int b){ //faster euclidean algorithm-see GCD for explanation

soltrinox

public static Boolean isPrime(int num){ //method signature. returns Boolean, true if number isPrime, false if not
    if(num==2){ //for case num=2, function returns true. detailed explanation underneath
      return(true);
    }
    for(int i=2;i<=(int)Math.sqrt(num)+1;i++){ //loops through 2 to sqrt(num). All you need to check- efficient
      if(num%i==0){ //if a divisor is found, its not prime. returns false
        return(false);
      }
    }
    return(true); //if all cases don't divide num, it is prime.

soltrinox

public static int fibonacci(int num){ //non-recursive fibonacci. returns the nth fibonacci number.
    double phi= (1+Math.sqrt(5))/2; 
    return((int)((Math.pow(phi,num)-Math.pow(1-phi,num))/Math.sqrt(5))); //finding fibonnaci number using formula.
  }
  public static int fibonacciRec(int num){ //recurive fibonacci. Used to demonstrate fibonacci
    if(num==1||num==2){ //stopping case. F(1)=1, F(2)=1 by definition.
      return(1);
    }
    return(fibonacciRec(num-1)+fibonacciRec(num-2)); //definition of Fibonacci sequence: F(n)=F(n-1)+F(n-2)
  }

soltrinox

public static void quicksort(int[] array)
  {  
    array = quicksort(array, 0, array.length-1);
  } 
  private static int[] quicksort(int[] array, int lo, int hi)   { 
      if (hi > lo)
      { 
        int partitionPivotIndex = (int)(Math.random()*(hi-lo) + lo);
        int newPivotIndex = partition(array, lo, hi, partitionPivotIndex);
        quicksort(array, lo, newPivotIndex-1);