Finish a few exercises

exercises/intro/intro1.rs

@@ -5,8 +5,6 @@
 // ready for the next exercise, remove the `I AM NOT DONE` comment below.
 // Execute the command `rustlings hint intro1` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);

exercises/intro/intro2.rs

@@ -2,8 +2,6 @@
 // Make the code print a greeting to the world.
 // Execute `rustlings hint intro2` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    println!("Hello {}!");
+    println!("Hello {}!", "world");
 }

exercises/variables/variables1.rs

@@ -2,9 +2,7 @@
 // Make me compile!
 // Execute the command `rustlings hint variables1` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }

exercises/variables/variables2.rs

@@ -1,10 +1,8 @@
 // variables2.rs
 // Make me compile! Execute the command `rustlings hint variables2` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    let x;
+    let x: i32 = 11;
     if x == 10 {
         println!("Ten!");
     } else {

exercises/variables/variables3.rs

@@ -1,10 +1,8 @@
 // variables3.rs
 // Make me compile! Execute the command `rustlings hint variables3` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    let x = 3;
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);

exercises/variables/variables4.rs

@@ -1,9 +1,7 @@
 // variables4.rs
 // Make me compile! Execute the command `rustlings hint variables4` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
-    let x: i32;
+    let x: i32 = 7;
     println!("Number {}", x);
 }

exercises/variables/variables5.rs

@@ -1,11 +1,9 @@
 // variables5.rs
 // Make me compile! Execute the command `rustlings hint variables5` if you want a hint :)
 
-// I AM NOT DONE
-
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3;
+    let number = 3;
     println!("Number plus two is : {}", number + 2);
 }

exercises/variables/variables6.rs

@@ -1,9 +1,7 @@
 // variables6.rs
 // Make me compile! Execute the command `rustlings hint variables6` if you want a hint :)
 
-// I AM NOT DONE
-
-const NUMBER = 3;
+const NUMBER: i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }