Add coding exercises for Facebook interviews

Add attempts at solving coding problems to Briefcase.

scratch/facebook/traversals.py

@@ -0,0 +1,100 @@
+from math import floor
+
+# Lists
+def cycle_backwards(times, xs):
+    n = len(xs)
+    for i in range(n * times):
+        print(xs[n - 1 - i % n])
+
+def cycle_forwards(times, xs):
+    n = len(xs)
+    for i in range(n * times):
+        print(xs[i % n])
+
+def backwards(xs):
+    n = len(xs)
+    for i in range(n):
+        print(xs[n - 1 - i])
+
+def forwards(xs):
+    for i in range(len(xs)):
+        print(xs[i])
+
+xs = [2, 5, 6, 9, 12]
+
+print("Forwards")
+forwards(xs)
+print("Backwards")
+backwards(xs)
+print("Cycle forwards")
+cycle_forwards(2, xs)
+print("Cycle backwards")
+cycle_backwards(2, xs)
+
+# Tables
+def tblr(table):
+    for row in range(len(table)):
+        for col in range(len(table[row])):
+            print(table[row][col])
+
+def tbrl(table):
+    for row in range(len(table)):
+        n = len(table[row])
+        for col in range(n):
+            print(table[row][n - 1 - col])
+
+def btlr(table):
+    n = len(table)
+    for row in range(n):
+        for col in range(len(table[row])):
+            print(table[n - 1 - row][col])
+
+def btrl(table):
+    rows = len(table)
+    for row in range(rows):
+        cols = len(table[row])
+        for col in range(cols):
+            print(table[rows - 1 - row][cols - 1 - col])
+
+def special(table):
+    rows = len(table)
+    cols = len(table[0])
+    for col in range(cols):
+        for row in range(rows):
+            print(table[row][col])
+
+def double_bonus(table):
+    rows = len(table)
+    cols = len(table[0])
+    for i in range(rows):
+        row = i
+        for col in range(cols):
+            print(table[row][col % cols])
+            row = (row + 1) % rows
+
+def free(table):
+    rows = len(table)
+    cols = len(table[0])
+    d = rows * cols
+    for i in range(d):
+        row = floor((i % d) / cols)
+        col = i % cols
+        print(table[row][col])
+
+table = [[1,2,3,4],
+         [5,6,7,8]]
+
+print("Top->Bottom, Left->Right")
+tblr(table)
+print("Top->Bottom, Right->Left")
+tbrl(table)
+print("Bottom->Top, Left->Right")
+btlr(table)
+print("Bottom->Top, Right->Left")
+btrl(table)
+print("Special")
+special(table)
+print("2x Bonus")
+double_bonus(table)
+print("Free")
+free(table)