Merge pull request #3259 from saurabh10041998/insert-delete-get-random

Create: 0380-insert-delete-getrandom.rs

Author: Ykhan799

rust/0380-insert-delete-getrandom-o1.rs

@@ -0,0 +1,40 @@
+use rand::seq::SliceRandom;
+use std::collections::HashMap;
+
+pub struct RandomizedSet {
+    mp: HashMap<i32, i32>,
+    arr: Vec<i32>,
+}
+
+impl RandomizedSet {
+    fn new() -> Self {
+        RandomizedSet {
+            mp: HashMap::new(),
+            arr: Vec::new(),
+        }
+    }
+
+    fn insert(&mut self, val: i32) -> bool {
+        let res = !self.mp.contains_key(&val);
+        if res {
+            self.mp.insert(val, self.arr.len() as i32);
+            self.arr.push(val);
+        }
+        res
+    }
+    fn remove(&mut self, val: i32) -> bool {
+        let res = self.mp.contains_key(&val);
+        if res {
+            let idx = *self.mp.get(&val).unwrap();
+            self.mp
+                .entry(*self.arr.last().unwrap())
+                .and_modify(|v| *v = idx);
+            self.arr.swap_remove(idx as usize);
+            self.mp.remove(&val);
+        }
+        res
+    }
+    fn get_random(&self) -> i32 {
+        *self.arr.choose(&mut rand::thread_rng()).unwrap()
+    }
+}