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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.