// Day 1.
// Good morning! Write a function that takes an array of strings and return the longest string in the array.
// For example:
// const strings1 = ['short', 'really, really long!', 'medium'];
// console.log(longestString(strings1)); // <--- 'really, really long!'
// Edge case: If you had an array which had two "longest" strings of equal length, your function should just return the first one.
// For example:

// const strings2 = ['short', 'first long string!!', 'medium', 'abcdefghijklmnopqr'];

// console.log(longestString(strings2)); // <--- 'first long string!'```

function longestString(arr) {
  return arr.reduce(function(acc, str) {
    return acc.length > str.length ? acc : str;
  });
}

// Day 2.
// Write a function called *reverseString* that accepts a string and returns a reversed copy of the string.

// Input Example:

// ```'hello world'
// 'asdf'
// 'CS rocks!'```

// Output Example:

// ```'dlrow olleh'
// 'fdsa'
// '!skcor SC'```

function reverseString(str) {
  return str.split("").reverse().join("");
}

// Day 3.
// Write a function called reverseNumber that reverses a number.

// ```Input Example:
// 54321
// 555

// Output Example:
// 12345
// 555```

function reverseNumber(num) {
  return parseInt(num.toString().split('').reverse().join('')) * Math.sign(num);
}

// The Math.sign() function returns the sign of a number, indicating whether the number is positive, negative or zero.

console.log(reverseNumber(54321)); // 12345
console.log(reverseNumber(-678)); // -876