# DGM Interview with Nadya

### Determine whether a string contains a backwards copy of another string.

const containsBackwards (a: string, b: string): boolean =>
    ;

#### Test Cases

containsBackwards("hello", "leh") === true;
containsBackwards("hello", "hel") === false;
containsBackwards("hello world", "w o") === true

function reverse(var str) {
    var split = str.split();
    
    var reverseArray = split.reverse();
    var joinArray = reverseArray.join("");
    
    var test1 = ("hello world").substr(6, 9);
    test1.join(" ");
    
    return joinArray();
    
}

/*
 * return whether `a` returns a backwards copy of `b`
 */
function containsBackwards(var a, var b): boolean {
    return reverse(b).split().join("");
    
}

### Fix the bug in this function that converts a list of vectors into a list of points.

class Vector {
    constructor (dx, dy) {
        this.dx = dx;
        this.dy = dy;
    }
    addToPoint(p: Point) {
        return new Point(p.getX() + this.dx, p.getY() + this.dy);
    }
}

/*
 * Convert a list of vectors into a list of points,
 * starting from 0,0, and in the same order as the list of vectors
 */
const makeAbsoluteReverse = (vs: Vector[]): Point[] =>
    vs.reduce(([prev, ...rest]: Point[], v: Vector) =>
        [v.addToPoint(prev), prev, ...rest],
        [new Point(0,0)]);
        
const makeAbsolute = (vs: Vector[]): Point[] => makeAbsoluteReverse(vs).reverse();

> makeAbsolute([new Vector(5,4), newVector(-4,3)])
[new Point(0,0), new Point(5,4), new Point(1,7)]

type Vector = {
    dx: number,
    dy; number,
};

type Point = {
    x: number,
    y: number,
};

/*
 * Convert a list of vectors into a list of points,
 * starting from 0,0, and in the same order as the list of vectors
 */
const makeAbsolute = (vs: Vector[]): Point[] =>
    vs.reduce(([prev, ...rest]: Point[], v: Vector) => [{
        x: prev.x + v.dx,
        y: prev.y + v.dy,
    }, prev, ...rest], {x: 0, y: 0});

### Given an array of numbers, return the greatest number without using sort.

const greatest = (ns: number[]): number => ;

function myMax (var test) {
    return Math.max(test);
}

arr.length ? Math.max(...arr) : 0
arr.length ? Math.max.apply(null, arr) : 0)

Math.max.apply(null, []) => -Infinity

myMax([])

myMax(["1", 2])

type NonEmpty<T> = [T, ...T];
function myMax (var test: NonEmpty<numbers>) /*...*/

### Given an array of numbers, return the second greatest number without using sort.

function test<T>(arr: [T, T, ...T]) {
 if (arr.length < 2) {
     /* do something */
 }
 var max = Math.max.apply(null, arr);
 arr.splice (arr.indexOf(max), 1);
 return Math.max.apply(null, arr);
}

test([0]);

test([0,1]);

### What's your preferred way to manage state?

* How would you manage state to make undo easy to implement?

const initialState = /*...*/;
let events = [];
function recieveEvent(ev){
    events.push(ev);
    /*...*/
}

function undo(){
    resetToInitialState();
    events.pop();
    event.forEach(recieveEvent);
}