Add word-search exercise

config.json

@@ -429,6 +429,14 @@
       "difficulty": 1,
       "topics": [
       ]
+    },
+    {
+      "slug": "word-search",
+      "difficulty": 6,
+      "topics": [
+        "strings",
+        "searching"
+      ]
     }
   ],
   "deprecated": [

exercises/word-search/example.py

@@ -0,0 +1,57 @@
+import copy
+
+
+class Point(object):
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __repr__(self):
+        return 'Point({}:{})'.format(self.x, self.y)
+
+    def __add__(self, other):
+        return Point(self.x + other.x, self.y + other.y)
+
+    def __sub__(self, other):
+        return Point(self.x - other.x, self.y - other.y)
+
+    def __eq__(self, other):
+        return self.x == other.x and self.y == other.y
+
+    def __ne__(self, other):
+        return not(self == other)
+
+
+DIRECTIONS = (Point(1, 0), Point(1, -1), Point(1, 1), Point(-1, -1),
+              Point(0, -1), Point(0, 1), Point(-1, 1), Point(-1, 0))
+
+
+class WordSearch(object):
+    def __init__(self, puzzle):
+        self.rows = puzzle.split()
+        self.width = len(self.rows[0])
+        self.height = len(self.rows)
+
+    def find_char(self, coordinate):
+        if coordinate.x < 0 or coordinate.x >= self.width:
+            return
+        if coordinate.y < 0 or coordinate.y >= self.height:
+            return
+        return self.rows[coordinate.y][coordinate.x]
+
+    def find(self, word, position, direction):
+            current = copy.copy(position)
+            for letter in word:
+                if self.find_char(current) != letter:
+                    return
+                current += direction
+            return position, current - direction
+
+    def search(self, word):
+        positions = (Point(x, y) for x in range(self.width) for y in range(self.height))
+        for pos in positions:
+            for d in DIRECTIONS:
+                result = self.find(word, pos, d)
+                if result:
+                    return result
+        return None

exercises/word-search/word_search.py

@@ -0,0 +1,27 @@
+class Point(object):
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __repr__(self):
+        return 'Point({}:{})'.format(self.x, self.y)
+
+    def __add__(self, other):
+        return Point(self.x + other.x, self.y + other.y)
+
+    def __sub__(self, other):
+        return Point(self.x - other.x, self.y - other.y)
+
+    def __eq__(self, other):
+        return self.x == other.x and self.y == other.y
+
+    def __ne__(self, other):
+        return not(self == other)
+
+
+class WordSearch(object):
+    def __init__(self, puzzle):
+        pass
+
+    def search(self, word):
+        return None

exercises/word-search/word_search_test.py

@@ -0,0 +1,84 @@
+import unittest
+
+from word_search import WordSearch, Point
+
+
+class WordSearchTests(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(self):
+        puzzle = ('jefblpepre\n'
+                  'camdcimgtc\n'
+                  'oivokprjsm\n'
+                  'pbwasqroua\n'
+                  'rixilelhrs\n'
+                  'wolcqlirpc\n'
+                  'screeaumgr\n'
+                  'alxhpburyi\n'
+                  'jalaycalmp\n'
+                  'clojurermt')
+        self.example = WordSearch(puzzle)
+
+    def test_horizontal_words_left_to_right(self):
+        self.assertEqual(
+            self.example.search('clojure'),
+            (Point(0, 9), Point(6, 9))
+        )
+
+    def test_horizontal_words_right_to_left(self):
+        self.assertEqual(
+            self.example.search('elixir'),
+            (Point(5, 4), Point(0, 4))
+        )
+
+    def test_vertical_words_top_to_bottom(self):
+        self.assertEqual(
+            self.example.search('ecmascript'),
+            (Point(9, 0), Point(9, 9))
+        )
+
+    def test_vertical_words_bottom_to_top(self):
+        self.assertEqual(
+            self.example.search('rust'),
+            (Point(8, 4), Point(8, 1))
+        )
+
+    def test_diagonal_words_top_left_to_bottom_right(self):
+        self.assertEqual(
+            self.example.search('java'),
+            (Point(0, 0), Point(3, 3))
+        )
+
+    def test_diagonal_upper_bottom_right_to_top_left(self):
+        self.assertEqual(
+            self.example.search('lua'),
+            (Point(7, 8), Point(5, 6))
+        )
+
+    def test_diagonal_upper_bottom_left_to_top_right(self):
+        self.assertEqual(
+            self.example.search('lisp'),
+            (Point(2, 5), Point(5, 2))
+        )
+
+    def test_diagonal_upper_top_right_to_bottom_left(self):
+        self.assertEqual(
+            self.example.search('ruby'),
+            (Point(7, 5), Point(4, 8))
+        )
+
+    def test_words_that_are_not_in_the_puzzle(self):
+        self.assertIsNone(self.example.search('haskell'))
+
+    def test_search_differently_sized_puzzles(self):
+        puzzle = ('qwertyuiopz\n'
+                  'luamsicrexe\n'
+                  'abcdefghijk')
+        self.assertEqual(
+            WordSearch(puzzle).search('exercism'),
+            (Point(10, 1), Point(3, 1))
+        )
+
+
+if __name__ == '__main__':
+    unittest.main()