Submitted: November 11, 2008        Views: 1215

Submitted: July 5, 2009        Views: 2053

given n and r, the snippet calculates the number of different permutations to choose r elements from n elements. The formula for P(n, r) = n!/(n-r)! but of course if n is large it will be very inefficient to compute the factorial first then plug it in the formula, instead we can use this property that P(n, r) = P(n, r-1)*n-(r-1) and that P(n, 0) = 1 and P(n, 1) = n. it can be done using an array of size r and on each iteration we look at the previous cell which holds the value for p(n,i-1) or to save memory we can instead accumulate the result in a variable.

Submitted: March 29, 2009        Views: 9375

a snippet in PROLOG that checks if a number is prime or not

Submitted: July 1, 2009        Views: 4217

just a small snippet to compute the binomial Coefficient nCk.. mathematically to compute the binomial coefficient ncK = n!/k!(n-k)! but if n is too large, computing it will be very inefficient, instead there's a recursive formula nCk = (n-1)C(k-1)+(n-1)Ck, so this can be used in a dynamic programming approach...also to speed things up, binomial Coefficients have this identity that nCk = nC(n-k), so we can use this to minimize the number of terms computed

Submitted: March 27, 2009        Views: 6416

the predicate returns true if Y is the factorial of X

Submitted: November 15, 2008        Views: 2499

my solution to a problem that i solved on www.projecteuler.net...this method sums the even terms in the fibonacci series that aren't greater than n

Submitted: March 25, 2009        Views: 14600

an example of the fibonacci series in prolog, the function will return true, if Y is the fibonacci value of X

Submitted: April 9, 2009        Views: 9775

a snippet that lists all the possible permutations of a list

Submitted: March 25, 2009        Views: 5712

a simple snippet in prolog to find the greatest common divisor of 2 numbers

Submitted: April 20, 2009        Views: 5525

the predicate insertionsort returns true if R is the sorted list of [H|T]

Submitted: August 8, 2009        Views: 623

a snippet that evaluates and simplifies logical expressions

Submitted: August 23, 2010        Views: 1421

This snippet finds the maximum non-negative sum of contiguous elements in an array, using Kadane's algorithm. This algorithm is an example of a greedy algorithm, the running time is O(n)

Submitted: November 29, 2008        Views: 2175

checks whether a string is a palindrome or not..a palindrome is a string that could be read backwards the same way it could be read forward example: mom dad

Submitted: January 3, 2009        Views: 22639

checks if the given string is a palindrome using recursion.

Submitted: December 29, 2008        Views: 2360

a small algorithm to find the prime factors of a number

Submitted: April 21, 2009        Views: 4267

the function isprime finds if the number is prime or not

Submitted: April 9, 2009        Views: 6902

a simple snippet to reverse a list in prolog

Submitted: February 18, 2009        Views: 6810

Submitted: April 20, 2009        Views: 3662

the predicate returns true if [X|Z] is the ordered representation of list R

Submitted: September 15, 2009        Views: 1057

finding all permutations of a string recursively

Submitted: November 19, 2008        Views: 12657

this method takes an integer as an argument and returns the sum of digits in that integer. Example: if the integer is 123, the method will return 1+2+3 = 6.

Submitted: March 29, 2009        Views: 4084

a simple snippet to find the sum of digits of a given number in PROLOG