vault backup: 2023-09-14 21:33:26

Algo/Séminaire/Exercices seminaire.md

@@ -305,3 +305,40 @@ let rec quo a b =
 	else 
 		1 + quo (a-b) b ;;
 ```
+
+## Exercise 4.9
+```Ocaml
+let rec reverse n = 
+	let str_n = string_of_int n in 
+	let len = String.length str_n in 
+	let rec reverse_helper index = 
+		if index < 0 then 
+			"" 
+		else 
+			String.make 1 str_n.[index] ^ reverse_helper (index - 1) 
+	in 
+	reverse_helper (len - 1) ;;
+
+let rec reverse_int n = 
+	let rec reverse_helper acc remaining = 
+	if remaining = 0 then 
+		acc 
+	else 
+		let last_digit = remaining mod 10 in 
+		let new_acc = acc * 10 + last_digit in 
+		let new_remaining = remaining / 10 
+	in reverse_helper new_acc new_remaining in reverse_helper 0 n ;;
+
+```
+
+## Exercise 4.10
+
+```Ocaml
+let rec multiply x y =
+  if x = 0 || y = 0 then
+    0
+  else if x mod 2 = 0 then
+    multiply (x / 2) (y * 2)
+  else
+    y + multiply (x / 2) (y * 2)
+```