update

ch05/ex8.go

@@ -0,0 +1,44 @@
+// find max in sorted rotated list
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	// assume increasing array
+	// and members >= 3
+	arr1 := []int{9,0,1,2,3,5,6,7,8}
+	fmt.Println(findMax(arr1))
+	arr2 := []int{8,9,0,1,2,3,5,6,7}
+	fmt.Println(findMax(arr2))
+	arr3 := []int{1,2,3,5,6,7,8,9,0}
+	fmt.Println(findMax(arr3))
+	arr4 := []int{2,3,5,6,7,8,9,0,1}
+	fmt.Println(findMax(arr4))
+}
+
+func findMax(arr []int) (index int) {
+	start := 0
+	end := len(arr) - 1
+
+	for start < end {
+		index = (start + end) / 2
+		if end == start + 1 {
+			if arr[index] < arr[index + 1] {
+				index += 1
+			}
+			break
+		}
+		if arr[index - 1] < arr[index] && arr[index] > arr[index + 1] {
+			break
+		}
+
+		if arr[index] < arr[start] {// on second group
+			end = index - 1
+		} else { // on first group
+			start = index + 1
+		}
+	}
+	return
+}

ch05/ex9.go

@@ -0,0 +1,44 @@
+// find min in sorted rotated list
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	// assume increasing array
+	// and members >= 3
+	arr1 := []int{9,0,1,2,3,5,6,7,8}
+	fmt.Println(findMin(arr1))
+	arr2 := []int{8,9,0,1,2,3,5,6,7}
+	fmt.Println(findMin(arr2))
+	arr3 := []int{1,2,3,5,6,7,8,9,0}
+	fmt.Println(findMin(arr3))
+	arr4 := []int{2,3,5,6,7,8,9,0,1}
+	fmt.Println(findMin(arr4))
+}
+
+func findMin(arr []int) (index int) {
+	start := 0
+	end := len(arr) - 1
+
+	for start < end {
+		index = (start + end) / 2
+		if start + 1 == end {
+			if arr[index] > arr[index + 1] {
+				index ++
+			}
+			break
+		}
+		if arr[index - 1] > arr[index] && arr[index] < arr[index + 1] {
+			break
+		}
+
+		if arr[index] > arr[end] { // on first group
+			start = index + 1
+		} else { // on second group
+			end = index - 1
+		}
+	}
+	return
+}