91 lines
2.0 KiB
Rust
91 lines
2.0 KiB
Rust
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/**
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* [380] Insert Delete GetRandom O(1)
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*/
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pub struct Solution {}
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// submission codes start here
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use rand::{rngs::ThreadRng, Rng};
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use std::collections::HashMap;
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struct RandomizedSet {
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array: Vec<i32>,
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pos_table: HashMap<i32, usize>,
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pos_now: usize,
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rng: ThreadRng
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}
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/**
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* `&self` means the method takes an immutable reference.
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* If you need a mutable reference, change it to `&mut self` instead.
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*/
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impl RandomizedSet {
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fn new() -> Self {
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RandomizedSet {
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array: vec![0;200_001],
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pos_table: HashMap::new(),
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pos_now: 0,
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rng: rand::thread_rng()
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}
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}
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fn insert(&mut self, val: i32) -> bool {
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if self.pos_table.contains_key(&val) {
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return false;
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}
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self.array[self.pos_now] = val;
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self.pos_table.insert(val, self.pos_now);
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self.pos_now += 1;
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true
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}
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fn remove(&mut self, val: i32) -> bool {
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return match self.pos_table.get(&val) {
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Some(&pos) => {
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let last = self.array[self.pos_now - 1];
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self.pos_table.insert(last, pos);
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self.array[pos] = last;
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self.pos_now -= 1;
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self.pos_table.remove(&val);
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true
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},
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None => false
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}
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}
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fn get_random(&mut self) -> i32 {
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let pos = self.rng.gen_range(0..self.pos_now);
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self.array[pos]
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}
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}
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/**
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* Your RandomizedSet object will be instantiated and called as such:
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* let obj = RandomizedSet::new();
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* let ret_1: bool = obj.insert(val);
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* let ret_2: bool = obj.remove(val);
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* let ret_3: i32 = obj.get_random();
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*/
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_380() {
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let mut set = RandomizedSet::new();
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assert!(set.insert(0));
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assert!(set.insert(1));
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assert!(set.remove(0));
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assert!(set.insert(2));
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assert!(set.remove(1));
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assert_eq!(2, set.get_random());
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}
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}
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