add to map

single_file_tests/vec.rs

@@ -1,3 +1,4 @@
+use std::collections::BTreeMap;
 
 fn main() {
     let v = vec![1, 3, 5];
@@ -21,5 +22,10 @@ fn main() {
     let v3: Vec<i32> = (0..3).collect();
     let v4 = v3.iter().map(|&x| x * 2).collect::<Vec<_>>();
     println!("{:?} -> {:?}", v3, v4);
+
+    println!("To Map:");
+    let v = (0..5).collect::<Vec<i32>>();
+    let m = v.iter().map(|i| (*i, i * 10)).collect::<BTreeMap<i32, i32>>();
+    println!("{:?}", m);
 }