diff --git a/docs/Chap09/9.3.md b/docs/Chap09/9.3.md
index c2f53dc6a4..f346293a7b 100755
--- a/docs/Chap09/9.3.md
+++ b/docs/Chap09/9.3.md
@@ -72,8 +72,8 @@ Pre-calculate the positions of the quantiles in $O(k)$, we use the $O(n)$ select
 ```cpp
 PARTITION(A, p, r)
     x = A[r]
-    i = p
-    for k = p to r
+    i = p - 1
+    for k = p to r - 1
         if A[k] < x
             i = i + 1
             swap A[i] with A[k]
@@ -99,7 +99,7 @@ RANDOMIZED-SELECT(A, p, r, i)
         if i == k
             return q, A[q]
         if i < k
-            r = q
+            r = q - 1
         else
             p = q + 1
             i = i - k
@@ -111,6 +111,8 @@ k-QUANTITLES-SUB(A, p, r, pos, f, e, quantiles)
         return
     mid = (f + e) / 2
     q, val = RANDOMIZED-SELECT(A, p, r, pos[mid])
+    if mid - 1 >= f
+        k-QUANTILES-SUB(A, p, q, pos, f, mid - 1, quantiles)
     quantiles[mid] = val
     k = q - p + 1
     for i = mid + 1 to e
@@ -120,15 +122,18 @@ k-QUANTITLES-SUB(A, p, r, pos, f, e, quantiles)
 
 ```cpp
 k-QUANTITLES(A, k)
+    if k == 1
+        return []
+
     num = A.size() / k
     mod = A.size() % k
-    pos = num[1..k]
-    for i = 1 to mod
-        pos[i] = pos[i] + 1
-    for i = 1 to k
+    pos = [1..(k-1)]
+    for i = 1 to k - 1
+        pos[i] = i <= mod ? num + 1 : num
+    for i = 2 to k - 1
         pos[i] = pos[i] + pos[i - 1]
-    quantiles = [1..k]
-    k-QUANTITLES-SUB(A, 0, A.length, pos, 0, pos.size(), quantiles)
+    quantiles = [1..(k-1)]
+    k-QUANTITLES-SUB(A, 1, A.length, pos, 1, pos.size(), quantiles)
     return quantiles
 ```