MILESTONE 1: Complete Arcade Intro CodeSignal

Last week was really crazy with me. But everything is okay now. And here we go.

DONE: 15/60

Day04: I stuck on challenge 4 (ReverseInParentheses). And then I cannot stuck on it anymore. I decide to check the answer.

Here is what I learn:

Challenge 10: reverseInParentheses

Here is highest point solution in JS:

function reverseInParentheses(s) {
  while (true) {
    const closedIndex = s.indexOf(")");

    if (closedIndex === -1) {
      break;
    }

    const openIndex = s.substring(0, closedIndex).lastIndexOf("(");

    const start = s.substring(0, openIndex);
    const middle = s
      .substring(openIndex + 1, closedIndex)
      .split("")
      .reverse("")
      .join("");
    const end = s.substring(closedIndex + 1, s.length);

    s = start + middle + end;
  }
  return s;
}

What I learn here:

• I learn the logic to find out which string should be reverse first.

Challenge 11: alternatingSums

Here is my solution:

function alternatingSums(a) {
    return a.reduce((acc, curr, index) => {
       if(index % 2 == 0) {
          acc[0] += curr 
       } else acc[1] += curr;

        return acc;
    }, [0, 0])
}

I findout the way to use reduce for this problem.

Here is highest point solution in JS:

alternatingSums = a => a.reduce((p,v,i) => (p[i&1]+=v,p), [0,0])

What I learn here:

• I learn about & operator in JS. But this is kinda complex to read and understand.

Challenge 12: addBorder

Here is my solution:

function addBorder(picture) {
  const initalElementLength = picture[0].length;
  picture = picture.map((el) => {
    return `*${el}*`;
  });

  let borderTopDown = "**";
  for (let i = 0; i < initalElementLength; i++) {
    borderTopDown += "*";
  }
  picture.push(borderTopDown);
  picture.unshift(borderTopDown);

  return picture;
}

This challenge kinda simple.

Here is highest point solution in JS:

function addBorder(picture) {
  var width = picture[0].length + 2;
  return [
    "*".repeat(width),
    ...picture.map((line) => `*${line}*`),
    "*".repeat(width),
  ];
}

What I learn here:

• Try to loop only one when use this.
• The repeat() method of string.

Okay. I done for today. I hope tomorrow will be better. Let's go.

#inanotherlife