155. Min Stack

1class MinStack {
2    stack: number[];
3    min_stack: number[];
4
5    constructor() {
6        this.stack = [];
7        this.min_stack = [Infinity]
8    }
9
10    push(val: number): void {
11        this.stack.push(val);
12        this.min_stack.push(Math.min(val, this.min_stack.at(-1)));
13    }
14
15    pop(): void {
16        this.stack.pop();
17        this.min_stack.pop();
18    }
19
20    top(): number {
21        return this.stack.at(-1)
22    }
23
24    getMin(): number {
25        return this.min_stack.at(-1)
26    }
27}
28
29/**
30 * Your MinStack object will be instantiated and called as such:
31 * var obj = new MinStack()
32 * obj.push(val)
33 * obj.pop()
34 * var param_3 = obj.top()
35 * var param_4 = obj.getMin()
36 */