complete threads till 06

exercises/07_threads/01_threads/src/lib.rs

@@ -15,7 +15,14 @@
 use std::thread;
 
 pub fn sum(v: Vec<i32>) -> i32 {
-    todo!()
+    // let mut c1 = (v.clone()[..v.len() / 2]).iter().collect::<Vec<_>>();
+    // let mut c2 = (v.clone()[v.len() / 2..]).iter().collect::<Vec<_>>();
+    let (c1, c2) = v.split_at(v.len() / 2);
+    let c1 = c1.to_vec();
+    let c2 = c2.to_vec();
+    let t1 = std::thread::spawn(move || c1.iter().sum::<i32>());
+    let t2 = std::thread::spawn(move || c2.iter().sum::<i32>());
+    t1.join().unwrap() + t2.join().unwrap()
 }
 
 #[cfg(test)]