Review Queues (#175)

Add diagram to queues.
Add examples to queue rehearsal problems

Author: spring1843

queue/README.md

@@ -6,6 +6,39 @@ In the real world, queues are formed when a first-come, first-served service is
 
 Another variation of queues is the double-ended queue, which allows for dequeuing from both ends, facilitating both FIFO and LIFO (Last In, First Out) data structures.
 
+The following diagram shows the state of a queue of size 5 when numbers 1 to 4 are enqueued and then 4 enqueues happen. The outcome is 4 numbers extracted in the same order they were inserted.
+
+```ASCII
+[Figure 1] Enqueue 1,2,3,4 to a queue and then dequeue 4 times
+  ┌───┬───┬───┬───┬───┐
+  │   │   │   │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 1 │   │   │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 1 │ 2 │   │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 1 │ 2 │ 3 │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 1 │ 2 │ 3 │ 4 │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 2 │ 3 │ 4 │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 3 │ 4 │   │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │ 4 │   │   │   │   │
+  └───┴───┴───┴───┴───┘
+  ┌───┬───┬───┬───┬───┐
+  │   │   │   │   │   │
+  └───┴───┴───┴───┴───┘
+```
+
 ## Implementation
 
 Like [stacks](../stack), queues can be implemented using doubly [linked lists](../linkedlist/) or [arrays and slices](../array/). Here is a linked list implementation:

queue/generate_binary_numbers_test.go

@@ -7,7 +7,9 @@ TestGenerateBinaryNumbers tests solution(s) with the following signature and pro
 
 	func GenerateBinaryNumbers(n int) []string
 
-Given a number n (n>=0) count from 0 to n in binary.
+Given a positive integer like n count from 0 to n in binary.
+
+For example given 3 return {"0", "1", "10", "11"}.
 */
 func TestGenerateBinaryNumbers(t *testing.T) {
 	tests := []struct {

queue/max_of_sub_arrays_test.go

@@ -10,10 +10,10 @@ TestMaxOfKLengthSubArrays tests solution(s) with the following signature and pro
 
 	func MaxOfKLengthSubArrays(numbers []int, k int) ([]int, error)
 
-Given a slice of numbers and an integer k, return a slice containing the maximum in each k-sized
+Given a slice of integers and an integer k, return a slice containing the maximum in each k-sized
 sub-array (sub-slice) of the input.
 
-For example given {1,2,3,4,5} and k=2, return {2,3,4,5} because:
+For example given {1,2,3,4,5} and k=2 return {2,3,4,5} because:
 
 * Sub-arrays of the input with length 2 are {{1,2},{2,3},{3,4},{4,5}}
 * The maximum in each of the sub-arrays is {2,3,4,5}.

queue/queue_using_stacks_test.go

@@ -12,7 +12,7 @@ TestQueueUsingStacks tests solution(s) with the following signature and problem
 	(usingStacks *UsingStacks) enqueue(n int)
 	(usingStacks *UsingStacks) dequeue() int
 
-Implement a queue of integers using stacks.
+Implement a queue of integers using two stacks. The queue should support enqueue and dequeue operations.
 */
 func TestQueueUsingStacks(t *testing.T) {
 	tests := []struct {

queue/string_permutations_test.go

@@ -10,8 +10,10 @@ TestStringPermutations tests solution(s) with the following signature and proble
 
 	func StringPermutations(input string) []string
 
-Given a string like "abc", return all possible permutations like "abc,acb,bac,bca,cab,cba" using
-a queue.
+Given a string return all possible permutations that can be made by rearranging the letters in the string
+using a queue.
+
+For example given "abc" return "abc,acb,bac,bca,cab,cba".
 */
 func TestStringPermutations(t *testing.T) {
 	tests := []struct {

queue/symmetrical_binary_tree_test.go

@@ -11,14 +11,19 @@ TestIsTreeSymmetrical tests solution(s) with the following signature and problem
 
 	func IsTreeSymmetrical(root *tree.BinaryTreeNode) (bool, error)
 
-Given a binary tree the one above "2,4,4,5,6,6,5", true if it is symmetric (mirrored from the root), and false otherwise.
+Given a binary tree return true of it is symmetric and false otherwise. A tree is symmetric if you
+can draw a vertical line through the root and then the left subtree is the mirror image of the right subtree.
 
-		     2
-		   /   \
-		  /     \
-		 4       4
-		/ \     / \
-	   5   6   6   5
+		 Symmetric       Not Symmetric
+		     2                2
+		   /   \            /   \
+		  /     \          /     \
+		 4       4        3       4
+		/ \     / \      / \     / \
+	   5   6   6   5    5   6   6   5
+
+For example given "2,4,4,5,6,6,5", shown in the symmetric tree above return true.
+Given "2,3,4,5,6,6,5", shown in the not symmetric tree above return false.
 */
 func TestIsTreeSymmetrical(t *testing.T) {
 	tests := []struct {