rs: add «2073. Time Needed to Buy Tickets»

Signed-off-by: Matej Focko <mfocko@redhat.com>

rs/time-needed-to-buy-tickets.rs

@@ -0,0 +1,16 @@
+use std::cmp;
+
+impl Solution {
+    pub fn time_required_to_buy(tickets: Vec<i32>, k: i32) -> i32 {
+        let threshold = tickets[k as usize];
+
+        let from_left: i32 = (0..=k as usize)
+            .map(|i| cmp::min(tickets[i], threshold))
+            .sum();
+        let from_right: i32 = (k as usize + 1..tickets.len())
+            .map(|i| cmp::min(tickets[i], threshold - 1))
+            .sum();
+
+        from_left + from_right
+    }
+}