Strings
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Given two booleans, make a function XOR, that returns whether those booleans are different, in 35 characters or less. Your function can't use != and == - that would be too easy.
XOR=(a,b)=>!!((a+b)%2)const chai = require("chai");
const assert = chai.assert;
describe("XOR", ()=> {
it("should return true for different bools", ()=> {
assert.strictEqual(XOR(true,false), true);
assert.strictEqual(XOR(false,true), true);
});
it("should return false for same bools", ()=> {
assert.strictEqual(XOR(true,true), false);
assert.strictEqual(XOR(false,false), false);
});
let fileContent = require("fs").readFileSync("/workspace/solution.txt", "utf8");
it("should be shorter than 30 characters", ()=> {
assert.isTrue(fileContent.length <= 35, `Your solution is ${fileContent.length-35} character${fileContent.length!=36 ? 's' : ''} over the length limit`);
})
it("shouldn't use !=(=) and ==(=)", ()=> {
assert.isFalse(fileContent.includes('!='), 'Your solution uses !=(=)');
assert.isFalse(fileContent.includes('=='), 'Your solution uses ==(=)');
})
it("should pass random tests", ()=> {
let a; let b;
for(let i=0;i<420;i++) {
a = Math.random() < 0.5;
b = Math.random() < 0.5;
assert.strictEqual(XOR(a,b), a != b);
}
})
});This will return a different value every time you call it, looping through numbers 1-4.
val = 0;
iter = () => {
val++;
if(val>4) val-=4;
return val;
}const chai = require("chai");
const assert = chai.assert;
describe("Iterating function", function() {
it("should loop over numbers", function() {
assert.strictEqual(iter(), 1);
assert.strictEqual(iter(), 2);
assert.strictEqual(iter(), 3);
assert.strictEqual(iter(), 4);
assert.strictEqual(iter(), 1);
assert.strictEqual(iter(), 2);
assert.strictEqual(iter(), 3);
assert.strictEqual(iter(), 4);
});
});Write a function to rotate a two-dimensional array 90 degrees clockwise, and name it rotateArray. The array is always a perfect rectangle.
const rotateArray = m => m[0].map((_,i)=>m.map(r=>r[i]).reverse());
// todo: make it work for empty arraysconst chai = require("chai");
const assert = chai.assert;
describe("Array Rotator", () => {
it("should rotate the array, i guess", () => {
assert.strictEqual(JSON.stringify(rotateArray([
[1,2],
[3,4]
])),JSON.stringify([
[3,1],
[4,2]
]));
assert.strictEqual(JSON.stringify(rotateArray([
[1,2,3],
[4,5,6]
])),JSON.stringify([
[4,1],
[5,2],
[6,3]
]));
assert.strictEqual(JSON.stringify(rotateArray([
[1,2],
[3,4],
[5,6]
])),JSON.stringify([
[5,3,1],
[6,4,2]
]));
});
});Come up with a creative way to replicate the functionality of Math.sign() (extra credits for not using the Math module at all).
The function should be named numberSign, and it should return +1 for positive numbers, -1 for negative, and 0 for 0.
const numberSign = x => x/Math.abs(x) || 0;const chai = require("chai");
const assert = chai.assert;
describe("Solution", () => {
it("should return 0 as is", () => {
assert.strictEqual(numberSign(0), 0);
assert.strictEqual(numberSign(-0), 0);
});
it("should return -1 for negative numbers", () => {
assert.strictEqual(numberSign(-4), -1);
assert.strictEqual(numberSign(-8), -1);
assert.strictEqual(numberSign(-82), -1);
assert.strictEqual(numberSign(-267), -1);
});
it("should return 1 for positive numbers", () => {
assert.strictEqual(numberSign(2), 1);
assert.strictEqual(numberSign(9), 1);
assert.strictEqual(numberSign(63), 1);
assert.strictEqual(numberSign(983), 1);
});
});