complete 2399.rs and rename storage/zeta/rust to rs

storage/zeta/rs/completed/2399.rs

@@ -0,0 +1,29 @@
+use std::io;
+use std::io::Write;
+
+fn mutual_difference(v: &Vec<i64>) -> i64 {
+    let mut s: i64 = 0;
+    for a in v {
+        for b in v {
+            s += (a - b).abs();
+        }
+    }
+    return s;
+}
+
+fn main() {
+    let stdout = io::stdout();
+    let mut out = io::BufWriter::new(stdout.lock());
+
+    let mut line = String::new();
+    let mut _trash = String::new();
+    io::stdin().read_line(&mut _trash).expect("err");
+    io::stdin().read_line(&mut line).expect("err");
+
+    let v = line
+        .trim()
+        .split(' ')
+        .map(|it| it.parse::<i64>().unwrap())
+        .collect::<Vec<i64>>();
+    writeln!(out, "{}", mutual_difference(&v)).expect("err");
+}