Creating a triangle number pattern in JavaScript with a loop

Question

Creating a triangle number pattern in JavaScript with a loop

Hi there, I'm currently facing an issue. I am trying to generate a triangular number pattern like the one shown below:

Output:
1223334444333221
=22333444433322=
===3334444333===
======4444======

I attempted to write a program for this, however, the logic I implemented is not working as expected.

function challengeAttempt(level) {
  let len = null;
  let result = [];
  while (level > 0) {
    let arr = [];
    for (let i = 1; i < level; i++) {
      for (let repeat = 0; repeat <i; repeat++){
        arr.push(i)
      }   
    }
// convert arr.push value from array to string using join
//and add 1 and the copy value using reverse
    let str_level = arr.join("") + "4444" + arr.reverse().join("");
    if (len == null) {
      len = str_level.length;
    }
    //Add Strip
    while (str_level.length < len) {
      str_level = "-" + str_level + "-";
    }
    result.push(str_level);
    level--;
  }
  return result.join("\n");
}

console.log(challengeAttempt(4))

If anyone can assist me with finding a solution, I would greatly appreciate it. Thank you!

javascript arrays loops for-loop while-loop

Answer 1

Answer №1

This unique approach utilizes a double nested method involving two map functions to iterate over arrays of rows (for row count) and columns (values to be displayed in each row).

const size = 4
const fill = '='
const rows = Array.from({length: size}, (_, i) => i + 1) // 1,2,3,4
const cols = rows.concat(rows.slice(0, -1).reverse())    // 1,2,3,4,3,2,1

const result = rows
  .map(r => cols
    .map(c => ((c >= r) ? c : fill).toString().repeat(c)
    ).join('')
  ).join('\n')

console.log(result)

Answer 2

This unique approach utilizes a double nested method involving two map functions to iterate over arrays of rows (for row count) and columns (values to be displayed in each row).

const size = 4
const fill = '='
const rows = Array.from({length: size}, (_, i) => i + 1) // 1,2,3,4
const cols = rows.concat(rows.slice(0, -1).reverse())    // 1,2,3,4,3,2,1

const result = rows
  .map(r => cols
    .map(c => ((c >= r) ? c : fill).toString().repeat(c)
    ).join('')
  ).join('\n')

console.log(result)

Answer 3

Answer №2

Although there are more efficient methods available, I am posting this to demonstrate how it can be done with minimal modifications from the original code (simply changing - to = and adjusting the for loop variable).

function number4(level) {
  let length = null;
  let output = [];
  while (level > 0) {
    let array = [];
    for (let index = 5-level; index < 4; index++) {
      for (let repeatCount = 0; repeatCount < index; repeatCount++){
        array.push(index);
      }   
    }
    // convert array values to a string using join
    // concatenate with "4444" and the reversed copy of the array
    let stringLevel = array.join("") + "4444" + array.reverse().join("");
    if (length == null) {
      length = stringLevel.length;
    }
    // Add equal signs to match the length
    while (stringLevel.length < length) {
      stringLevel = "=" + stringLevel + "=";
    }
    output.push(stringLevel);
    level--;
  }
  return output.join("\n");
}

console.log(number4(4))

Answer 4

Although there are more efficient methods available, I am posting this to demonstrate how it can be done with minimal modifications from the original code (simply changing - to = and adjusting the for loop variable).

function number4(level) {
  let length = null;
  let output = [];
  while (level > 0) {
    let array = [];
    for (let index = 5-level; index < 4; index++) {
      for (let repeatCount = 0; repeatCount < index; repeatCount++){
        array.push(index);
      }   
    }
    // convert array values to a string using join
    // concatenate with "4444" and the reversed copy of the array
    let stringLevel = array.join("") + "4444" + array.reverse().join("");
    if (length == null) {
      length = stringLevel.length;
    }
    // Add equal signs to match the length
    while (stringLevel.length < length) {
      stringLevel = "=" + stringLevel + "=";
    }
    output.push(stringLevel);
    level--;
  }
  return output.join("\n");
}

console.log(number4(4))

Answer 5

Answer №3

function generatePattern(level) {
  let value = level;
  let length = null;
  let patternArr = [];
  while (level >= 0) {
    let numArr = [];
    for (let i = 1; i <= value; i++) {
      if (value !== i) {
        for (let repeat = 0; repeat < i; repeat++) {
          if (value - level <= i) {
            numArr.push(i);
          }
        }
      }
    }
    // convert numArr values from array to string using join
    // and add 4444 in between and then reverse the array elements
    let str_pattern = numArr.join("") + "4444" + numArr.reverse().join("");
    if (length == null) {
      length = str_pattern.length;
    }
    // Add dashes to make all strings equal in length
    while (str_pattern.length < length) {
      str_pattern = "-" + str_pattern + "-";
    }
    patternArr.push(str_pattern);
    patternArr = [...new Set(patternArr)];
    level--;
  }
  return patternArr.join("\n");
}

console.log(generatePattern(4));

Answer 6

function generatePattern(level) {
  let value = level;
  let length = null;
  let patternArr = [];
  while (level >= 0) {
    let numArr = [];
    for (let i = 1; i <= value; i++) {
      if (value !== i) {
        for (let repeat = 0; repeat < i; repeat++) {
          if (value - level <= i) {
            numArr.push(i);
          }
        }
      }
    }
    // convert numArr values from array to string using join
    // and add 4444 in between and then reverse the array elements
    let str_pattern = numArr.join("") + "4444" + numArr.reverse().join("");
    if (length == null) {
      length = str_pattern.length;
    }
    // Add dashes to make all strings equal in length
    while (str_pattern.length < length) {
      str_pattern = "-" + str_pattern + "-";
    }
    patternArr.push(str_pattern);
    patternArr = [...new Set(patternArr)];
    level--;
  }
  return patternArr.join("\n");
}

console.log(generatePattern(4));

Creating a triangle number pattern in JavaScript with a loop

Answer №1

Answer №2

Answer №3

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