complete 2-2.2

2 files changed, 24 insertions, 2 deletions

diff --git a/exercises/2.2-2/selection_sort_test.go b/exercises/2.2-2/selection_sort_test.go
index e4abc5d..2b175e9 100644
--- a/exercises/2.2-2/selection_sort_test.go
+++ b/exercises/2.2-2/selection_sort_test.go
@@ -7,11 +7,13 @@ func Sort(i *[]int) {
 	n := len(A)
 
 	for i := 0; i < n; i++ {
+		min := i
 		for j := i + 1; j < n; j++ {
-			if A[j] < A[i] {
-				A[i], A[j] = A[j], A[i]
+			if A[j] < A[min] {
+				min = j
 			}
 		}
+		A[i], A[min] = A[min], A[i]
 	}
 }
 
diff --git a/notes.md b/notes.md
index 521d113..a8ba4c4 100644
--- a/notes.md
+++ b/notes.md
@@ -460,6 +460,26 @@ the rate of growth in determining computational efficiency for large inputs.
 > manner for the first `n - 1` elements of `A`.
 
     Write pseudocode for *selection sort*.
+
+      n = A.length
+      for i = 1 to n - 1 {
+        min = i
+        for j = i + 1 to n {
+          if A[j] < A[min]
+            min = j
+        A[i], A[min] = A[min], A[i]
+
+
     What loop invariant does this algorithm maintain?
+
+      * intialization: inner loop initializes to the right index of the outer loop
+      * maintenance: with the inner right array of the outer array.
+      * termination: when end of loop is reached
+
     Why does it need to run for only the first n-1 elements, rather than for all `n` elements?
+
+      * The last element of the array should has nothing to be compared against.
+
     Give the best-case and worst-case running times of selection sort in 𝚯-notation.
+
+      = 𝚯(n^2). two loops, one nested within the other.