2-answer.md

✅ Double Stack to solve the 🧑🏻‍💻 Min Stack Problem on 🦀 RUST language

🧑🏻‍💻 Approach

new(): This is the constructor method that creates a new instance of MinStack by initializing empty vectors for stack and min_stack using Vec::new().

push(&mut self, val: i32): This method takes an integer value val as a parameter and adds it to the top of the stack by using the push method of the stack vector. It also checks if the min_stack is empty or if the new value val is less than or equal to the current minimum value (*self.min_stack.last().unwrap()). If so, it pushes the new value val to the min_stack as well.

pop(&mut self): This method removes the top element from the stack by using the pop method of the stack vector. It also checks if the removed element is equal to the current minimum value (*self.min_stack.last().unwrap()). If so, it removes the minimum value from the min_stack as well.

top(&self) -> i32: This method returns the value of the top element of the stack without removing it. It uses the last method of the stack vector to get a reference to the last element and then dereferences it with * to obtain the value.

get_min(&self) -> i32: This method returns the minimum value in the stack by accessing the last element of the min_stack. It uses the last method of the min_stack vector to get a reference to the last element and then dereferences it with * to obtain the value.

🔐 Code

struct MinStack {
    stack:Vec<i32>,
    min_stack:Vec<i32>
}


/** 
 * `&self` means the method takes an immutable reference.
 * If you need a mutable reference, change it to `&mut self` instead.
 */
impl MinStack {

    fn new() -> Self {
        MinStack { stack: Vec::new(), min_stack: Vec::new() }
    }
    
    fn push(&mut self, val: i32) {
        self.stack.push(val);
        if self.min_stack.is_empty() || val <= *self.min_stack.last().unwrap(){
            self.min_stack.push(val)
        }
    }
    
    fn pop(&mut self) {
        if let Some(x) = self.stack.pop() {
            if x == *self.min_stack.last().unwrap() {
                self.min_stack.pop();
            }
        }
        
    }
    
    fn top(&self) -> i32 {
        *self.stack.last().unwrap()
    }
    
    fn get_min(&self) -> i32 {
        *self.min_stack.last().unwrap()
    }
}