LC:NN upload 5b

diff --git a/rust/q_sequence/src/main.rs b/rust/q_sequence/src/main.rs
new file mode 100644
--- /dev/null
+++ b/rust/q_sequence/src/main.rs
@@ -0,0 +1,59 @@
+use std::collections::HashMap;
+use std::sync::{Arc,RwLock};
+use std::thread;
+
+fn poll_for(mapping: Arc<RwLock<HashMap<i32, Arc<RwLock<i32>>>>>, key: i32) -> Arc<RwLock<i32>> {
+    loop {
+        match mapping.read().unwrap().get(&key) {
+            Some(i) => return i.clone(),
+            None => ()
+        }
+    }
+}
+
+fn q(mapping: &mut Arc<RwLock<HashMap<i32, Arc<RwLock<i32>>>>>, key: i32) -> i32 {
+    println!("Running for {:?}", key);
+    {
+        match mapping.read().unwrap().get(&key) {
+            Some(i) => return *i.read().unwrap(),
+            None => ()
+        }
+    }
+    {
+        println!("Generating for {:?}", key);
+        let lock = Arc::new(RwLock::new(0));
+        let mut val = lock.write().unwrap();
+        {
+            use std::collections::hash_map::Entry::*;
+            let mut mutable_mapping = mapping.write().unwrap();
+            match mutable_mapping.entry(key) {
+                Occupied(entry) => return *entry.get().read().unwrap(),
+                Vacant(entry) => {entry.insert(lock.clone());}
+            }
+            println!("Inserted for {:?}", key);
+        }
+        {
+            let mut _mapping = mapping.clone();
+            thread::spawn(move || {
+                q(&mut _mapping, key - 1);
+            });
+        }
+        {
+            let prev = poll_for(mapping.clone(), key - 1);
+            let prev_prev = poll_for(mapping.clone(), key - 2);
+            let first = poll_for(mapping.clone(), key - *prev.read().unwrap());
+            let second = poll_for(mapping.clone(), key - *prev_prev.read().unwrap());
+            *val = *first.read().unwrap() + *second.read().unwrap();
+        }
+        *val
+    }
+}
+
+fn main() {
+    let mut mapping = HashMap::new();
+    mapping.insert(1, Arc::new(RwLock::new(1)));
+    mapping.insert(2, Arc::new(RwLock::new(1)));
+    let mut mapping = Arc::new(RwLock::new(mapping));
+    println!("{:?}", q(&mut mapping, 10));
+    println!("{:?}", q(&mut mapping, 10));
+}