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hello-algo/codes/rust/chapter_stack_and_queue/array_deque.rs

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4.5 KiB

/*
* File: array_deque.rs
* Created Time: 2023-03-11
* Author: sjinzh (sjinzh@gmail.com)
*/
include!("../include/include.rs");
/* 基于环形数组实现的双向队列 */
struct ArrayDeque {
nums: Vec<i32>, // 用于存储双向队列元素的数组
front: usize, // 队首指针,指向队首元素
que_size: usize, // 双向队列长度
}
impl ArrayDeque {
/* 构造方法 */
pub fn new(capacity: usize) -> Self {
Self {
nums: vec![0; capacity],
front: 0,
que_size: 0,
}
}
/* 获取双向队列的容量 */
pub fn capacity(&self) -> usize {
self.nums.len()
}
/* 获取双向队列的长度 */
pub fn size(&self) -> usize {
self.que_size
}
/* 判断双向队列是否为空 */
pub fn is_empty(&self) -> bool {
self.que_size == 0
}
/* 计算环形数组索引 */
fn index(&self, i: i32) -> usize {
// 通过取余操作实现数组首尾相连
// 当 i 越过数组尾部后,回到头部
// 当 i 越过数组头部后,回到尾部
return ((i + self.capacity() as i32) % self.capacity() as i32) as usize;
}
/* 队首入队 */
pub fn push_first(&mut self, num: i32) {
if self.que_size == self.capacity() {
println!("双向队列已满");
return
}
// 队首指针向左移动一位
// 通过取余操作,实现 front 越过数组头部后回到尾部
self.front = self.index(self.front as i32 - 1);
// 将 num 添加至队首
self.nums[self.front] = num;
self.que_size += 1;
}
/* 队尾入队 */
pub fn push_last(&mut self, num: i32) {
if self.que_size == self.capacity() {
println!("双向队列已满");
return
}
// 计算尾指针,指向队尾索引 + 1
let rear = self.index(self.front as i32 + self.que_size as i32);
// 将 num 添加至队尾
self.nums[rear] = num;
self.que_size += 1;
}
/* 队首出队 */
fn pop_first(&mut self) -> i32 {
let num = self.peek_first();
// 队首指针向后移动一位
self.front = self.index(self.front as i32 + 1);
self.que_size -= 1;
num
}
/* 队尾出队 */
fn pop_last(&mut self) -> i32 {
let num = self.peek_last();
self.que_size -= 1;
num
}
/* 访问队首元素 */
fn peek_first(&self) -> i32 {
if self.is_empty() { panic!("双向队列为空") };
self.nums[self.front]
}
/* 访问队尾元素 */
fn peek_last(&self) -> i32 {
if self.is_empty() { panic!("双向队列为空") };
// 计算尾元素索引
let last = self.index(self.front as i32 + self.que_size as i32 - 1);
self.nums[last]
}
/* 返回数组用于打印 */
fn to_array(&self) -> Vec<i32> {
// 仅转换有效长度范围内的列表元素
let mut res = vec![0; self.que_size];
let mut j = self.front;
for i in 0..self.que_size {
res[i] = self.nums[self.index(j as i32)];
j += 1;
}
res
}
}
fn main() {
/* 初始化双向队列 */
let mut deque = ArrayDeque::new(10);
deque.push_last(3);
deque.push_last(2);
deque.push_last(5);
print!("双向队列 deque = ");
print_util::print_array(&deque.to_array());
/* 访问元素 */
let peek_first = deque.peek_first();
print!("\n队首元素 peek_first = {}", peek_first);
let peek_last = deque.peek_last();
print!("\n队尾元素 peek_last = {}", peek_last);
/* 元素入队 */
deque.push_last(4);
print!("\n元素 4 队尾入队后 deque = ");
print_util::print_array(&deque.to_array());
deque.push_first(1);
print!("\n元素 1 队首入队后 deque = ");
print_util::print_array(&deque.to_array());
/* 元素出队 */
let pop_last = deque.pop_last();
print!("\n队尾出队元素 = {},队尾出队后 deque = ", pop_last);
print_util::print_array(&deque.to_array());
let pop_first = deque.pop_first();
print!("\n队首出队元素 = {},队首出队后 deque = ", pop_first);
print_util::print_array(&deque.to_array());
/* 获取双向队列的长度 */
let size = deque.size();
print!("\n双向队列长度 size = {}", size);
/* 判断双向队列是否为空 */
let is_empty = deque.is_empty();
print!("\n双向队列是否为空 = {}", is_empty);
}