99 Elm Problems/Problems by Category

Lists Problem 1: Find the last element of a list Problem 2: Find the next to last element of a list Problem 3: Find the n-th element of a list Problem 4: Find the number of elements of a list Problem 5: Reverse a list Problem 6: Determine if a list is a palindrome Problem 7: Flatten a nested list structure Problem 8: Eliminate consecutive duplicates of list elements Problem 9: Pack consecutive duplicates of list elements into sublists Problem 10: Run length encode a list of tuples Lists, continued Problem 11: Run-length encoding Problem 12: Run-length decoding Problem 14: Duplicate the elements Problem 15: Repeat each element Problem 16: Drop every N'th element Problem 17: Split a list into two parts Problem 18: Extract a sublist Problem 19: Rotate a list N places Problem 20: Remove the nth element Lists again Problem 21: Insert an element Problem 22: Create a range of integers Problem 23: Randomly selected elements Problem 24: Randomly select from a set Problem 25: Generate a random permutation Problem 26: Generate combinations of a set Problem 27: Group elements into disjoint subsets Problem 28: Sort a list of lists Arithmetic Problem 31: Check for prime Problem 32: Find greatest common divisor Problem 33: Check for coprime Problem 34: Calculate Euler's totient function Problem 35: Find prime factors Problem 36: List the prime factors Problem 37: Calculate Euler's totient function using prime factors Problem 39: List prime numbers within a range Problem 40: Goldbach's conjecture Problem 41: Search a range of numbers Logic and Codes Problem 46: Define functions for logical operations Problem 47: Build truth tables for logical expressions Problem 48: Build truth tables for any logical expressions Problem 49: Gray codes Problem 50: Huffman codes Binary Trees Problem 55: Construct a balanced binary tree Problem 56: Construct a symmetric binary tree Problem 57: Construct a binary search tree Problem 58: Generate and test paradigm Problem 59: Construct a height balanced binary tree Problem 60: Construct a height-balanced binary tree of N nodes Binary Trees, continued Problem 61: Count the leaves Problem 62: Collect the internal nodes Problem 63: Construct a complete binary tree Problem 64: Plot node coordinates 1 Problem 65: Plot node coordinates 2 Problem 66: Plot node coordinates 3 Problem 67: Represent a tree as a string Problem 68: Generate an ordered sequence Problem 69: Represent a tree with Dot Notation Multi-way Trees Problem 70: Count the nodes of a multiway tree Problem 71: Internal path of a multiway tree Problem 72: Bottom-up sequence of a multiway tree Problem 73: Lisp representation of a multiway tree Graphs Problem 80: Convert graphs representations Problem 81: Find all cyclic paths Problem 82: Find closed paths Problem 83: Find spanning trees Problem 84: Find the minimal spanning tree Problem 85: Determine if two graphs are isomorphic Problem 86: Calculate degree of a node Problem 87: Depth-first order graph traversal Problem 88: Connected components Problem 89: Check for bipartite graph Puzzles Problem 90: Eight Queens Problem 91: The Knight's Tour Problem 92: Graceful Labeling Problem 93: Inserting operators Problem 94: Generate regular graphs Problem 95: Numbers to text Problem 96: Syntax checker Problem 97: Sudoku solver Problem 98: Nonogram solver Problem 99: Elm Problems: Crossword puzzle solver