MaxStack

class MaxStack {
    constructor() {
        this.results = [];
        this.sorted = [];
    }

    pop() {
        const val = this.results.pop();
        this.sorted.splice(this.sorted.lastIndexOf(val), 1);
        return val;
    }

    push(x) {
        this.results.push(x);
        this.sorted = [...this.results].sort((x, y) => x - y);
    }

    top() {
        return this.results[this.results.length - 1];
    }

    popMax() {
        const val = this.sorted.pop();
        this.results.splice(this.results.lastIndexOf(val), 1);
        return val;
    }

    peekMax() {
        return this.sorted[this.sorted.length - 1];
    }

}