<pre class="shiki github-dark shaku"><code>function noSignAdd(num1, num2) { let result = [], carry = 0 let idx1 = num1.length - 1, idx2 = num2.length - 1 while (idx1 &gt;= 0 || idx2 &gt;= 0 || carry) { const sum = Number(num1[idx1--] ?? 0) + Number(num2[idx2--] ?? 0) + carry result.unshift(sum % 10) carry = sum &gt; 9 ? 1 : 0 } return result.join('')}// num1 should greater than num2function noSignSubtract(num1, num2) { let result = [], carry = 0 let idx1 = num1.length - 1, idx2 = num2.length - 1 while (idx1 &gt;= 0 || idx2 &gt;= 0 || carry) { const diff = Number(num1[idx1--] ?? 0) - Number(num2[idx2--] ?? 0) + carry result.unshift((diff + 10) % 10) carry = diff &lt; 0 ? -1 : 0 } // Remove leading 0 while (result.length &gt; 1 &amp;&amp; result[0] === 0) { result.shift() } return result.join('')}function isAscending(num1, num2) { if (num1 === num2) { return 0 } const len1 = num1.length const len2 = num2.length if (len1 === len2) { let idx = 0 while (num1[idx] === num2[idx] &amp;&amp; idx &lt; len1) { idx++ } return num1[idx] &gt; num2[idx] ? 1 : -1 } return len1 &gt; len2 ? 1 : -1}/** * @param {string} num1 * @param {string} num2 * @return {string} */function subtract(num1, num2) { const sign1 = num1[0] === '-' ? num1[0] : '' // reversed const sign2 = num2[0] === '-' ? '' : '-' const abs1 = num1.replace(/[+-]/, '') const abs2 = num2.replace(/[+-]/, '') // Same sign if (sign1 === sign2) { return sign1 + noSignAdd(abs1, abs2) } // abs1 = abs2 if (abs1 === abs2) { return '0' } // abs1 &gt; abs2 if (isAscending(abs1, abs2) === 1) { return sign1 + noSignSubtract(abs1, abs2) } return sign2 + noSignSubtract(abs2, abs1)}</code></pre>

My accepted solution

This is a follow-up on 75. implement BigInt subtraction. You are asked to implement a string substraction function, with possible negative integers. A…