insert-delete-getrandom-o1-duplicates-allowed.rs

#![allow(dead_code, unused, unused_variables)]

use rand::Rng;

fnmain(){
letmut r = RandomizedCollection::new();
assert!(r.insert(1));
assert!(!r.insert(1));
assert!(r.insert(2));
assert!(r.remove(1));
println!("{}", r.get_random());
println!("{}", r.get_random());
println!("{}", r.get_random());
println!("{}", rand::thread_rng().gen_range(0..10));
println!("{}", rand::thread_rng().gen_range(0..10));
println!("{}", rand::thread_rng().gen_range(0..10));
println!("{}", rand::thread_rng().gen_range(0..10));
}

/**
 * Your RandomizedCollection object will be instantiated and called as such:
 * let obj = RandomizedCollection::new();
 * let ret_1: bool = obj.insert(val);
 * let ret_2: bool = obj.remove(val);
 * let ret_3: i32 = obj.get_random();
 */
structRandomizedCollection{
data:Vec<i32>,
indexes: std::collections::HashMap<i32, std::collections::HashMap<usize,()>>,
}

/**
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
implRandomizedCollection{
/** Initialize your data structure here. */
fnnew() -> Self{
Self{
data:Vec::new(),
indexes: std::collections::HashMap::new(),
}
}

/** Inserts a value to the collection. Returns true if the collection did not already contain the specified element. */
fninsert(&mutself,val:i32) -> bool{
let has = self.indexes.get(&val).is_some();
self.data.push(val);
let index = self.data.len() - 1;
self.indexes
.entry(val)
.and_modify(|i| {
 i.insert(index,());
})
.or_insert_with(|| {
letmut h = std::collections::HashMap::new();
 h.insert(index,());
 h
});

 !has
}

/** Removes a value from the collection. Returns true if the collection contained the specified element. */
fnremove(&mutself,val:i32) -> bool{
ifself.indexes.get(&val).is_none(){
returnfalse;
}

let index = {
let i = *self.indexes.get(&val).unwrap().keys().next().unwrap();
self.indexes.get_mut(&val).unwrap().remove(&i);
 i
};
let l = self.data.len() - 1;
let last = self.data[l];
self.data.swap(index, l);

if l != index {
self.indexes.entry(last).and_modify(|x| {
 x.remove(&l);
 x.insert(index,());
});
}

self.data.pop();

ifself.indexes.get(&val).unwrap().is_empty(){
self.indexes.remove(&val);
}

true
}

/** Get a random element from the collection. */
fnget_random(&self) -> i32{
use rand::Rng;
letmut rng = rand::thread_rng();
let index = rng.gen_range(0..self.data.len());
self.data[index]
}
}