update HashMap.md

solutions/collections/Hashmap.md

@@ -0,0 +1,73 @@
+1.
+```rust
+// FILL in the blanks and FIX the erros
+use std::collections::HashMap;
+fn main() {
+    let mut scores = HashMap::new();
+    scores.insert("Sunface", 98);
+    scores.insert("Daniel", 95);
+    scores.insert("Ashley", 69);
+    scores.insert("Katie", 58);
+
+    // get returns a Option<&V>
+    let score = scores.get("Sunface");
+    assert_eq!(score, Some(&98));
+
+    if scores.contains_key("Daniel") {
+        // indexing return a value V
+        let score = scores["Daniel"];
+        assert_eq!(score, 95);
+        scores.remove("Daniel");
+    }
+
+    assert_eq!(scores.len(), 3);
+
+    for (name, score) in scores {
+        println!("The score of {} is {}", name, score)
+    }
+}
+```
+
+2.
+```rust
+use std::collections::HashMap;
+fn main() {
+    let teams = [
+        ("Chinese Team", 100),
+        ("American Team", 10),
+        ("France Team", 50),
+    ];
+
+    let mut teams_map1 = HashMap::new();
+    for team in &teams {
+        teams_map1.insert(team.0, team.1);
+    }
+
+    let teams_map2: HashMap<_,_> = teams.into_iter().collect();
+
+    assert_eq!(teams_map1, teams_map2);
+
+    println!("Success!")
+}
+```
+
+```rust
+use std::{collections::HashMap};
+fn main() {
+    let teams = [
+        ("Chinese Team", 100),
+        ("American Team", 10),
+        ("France Team", 50),
+    ];
+
+    let mut teams_map1 = HashMap::new();
+    for team in &teams {
+        teams_map1.insert(team.0, team.1);
+    }
+
+    let teams_map2 = HashMap::from(teams);
+    assert_eq!(teams_map1, teams_map2);
+
+    println!("Success!")
+}
+```