54 lines
1.3 KiB
Rust
54 lines
1.3 KiB
Rust
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#[derive(Default)]
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struct MyQueue {
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front: Vec<i32>,
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back: Vec<i32>
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}
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// This solution has a maximum complexity of O(n) for
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// all the operations combined, but a single operation
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// could also be O(n) (apart from push and empty which
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// is always O(1))
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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 MyQueue {
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fn new() -> Self {
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Default::default()
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}
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fn flush(&mut self) {
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if self.front.is_empty() {
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while let Some(n) = self.back.pop() {
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self.front.push(n);
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}
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}
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}
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fn push(&mut self, x: i32) {
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self.back.push(x)
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}
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fn pop(&mut self) -> i32 {
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self.flush();
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self.front.pop().unwrap() // Unsafe unwrap because of instructions
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}
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fn peek(&mut self) -> i32 {
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self.flush();
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*self.front.last().unwrap() // Unsafe unwrap because of instructions
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}
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fn empty(&self) -> bool {
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self.front.is_empty() && self.back.is_empty()
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}
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}
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/**
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* Your MyQueue object will be instantiated and called as such:
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* let obj = MyQueue::new();
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* obj.push(x);
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* let ret_2: i32 = obj.pop();
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* let ret_3: i32 = obj.peek();
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* let ret_4: bool = obj.empty();
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*/
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