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‎ts/src/binary-tree/diameter-of-binary-tree.ts‎

Lines changed: 54 additions & 0 deletions
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import { TreeNode } from '../utils/nodes';
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function diameterOfBinaryTree(root: TreeNode | null): number {
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let max = 0;
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function dfs(root: TreeNode | null): number {
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if (!root) return 0;
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const l = dfs(root.left),
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r = dfs(root.right);
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max = Math.max(max, l + r);
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return Math.max(l, r) + 1;
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}
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dfs(root);
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return max;
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}
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// function isValidBST(root: TreeNode | null): boolean {
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// if (!root) return true;
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// if (root.left && root.left.val > root.val) return false;
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// if (root.right && root.right.val < root.val) return false;
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// const l = isValidBST(root.left), r = isValidBST(root.right);
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// return l && r;
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// }
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// function isValidBST(root: TreeNode | null, parent = root.val): boolean {
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// if (!root) return false;
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// if (root.left && (root.left.val >= root.val || root.left.val >= parent)) return false;
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// if (root.right && (root.right.val <= root.val || root.right.val <= parent)) return false;
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// return isValidBST(root.left, root.val) && isValidBST(root.right, root.val);
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// }
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function isValidBST(
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root: TreeNode | null,
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min: number | null = null,
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max: number | null = null
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): boolean {
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if (!root) return true;
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if ((min !== null && root.val <= min) || (max !== null && root.val >= max))
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return false;
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return ( isValidBST(root.left, min, root.val) && isValidBST(root.right, root.val, max));
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}
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const a = new TreeNode(7);
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const c = new TreeNode(3);
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const d = new TreeNode(6, c, a);
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const b = new TreeNode(4);
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const e = new TreeNode(5, b, d);
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console.log(isValidBST(e));
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const f = new TreeNode(1);
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const g = new TreeNode(3);
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const h = new TreeNode(2, f, g);
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// console.log(isValidBST(h));

‎ts/src/neetcode-150-practice/sliding-window/01_best-time-to-buy-and-sell-stock.ts‎

Lines changed: 9 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
1-
const maxProfit = (prices: number[]): number => {
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let curr = 0, max = 0, l = 0;
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for (let i = 1; i < prices.length; i++) {
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if (prices[l] < prices[i])
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(curr = prices[i] - prices[l]), (max = Math.max(curr, max));
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else l = i;
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}
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return max;
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};
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// const maxProfit = (prices: number[]): number => {
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// let curr = 0, max = 0, l = 0;
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// for (let i = 1; i < prices.length; i++) {
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// if (prices[l] < prices[i])
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// (curr = prices[i] - prices[l]), (max = Math.max(curr, max));
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// else l = i;
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// }
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// return max;
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// };

‎ts/src/neetcode-150-practice/sliding-window/02_longest-substring-without-repeating-characters.ts‎

Lines changed: 10 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,16 +1,17 @@
11
import { ITestCase, runTests } from '../../utils/tests';
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const lengthOfLongestSubstring = (s: string): number => {
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let max = 0, i = 0, charsSet = new Set<string>();
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for (let j = 0; j < s.length; j++) {
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const char = s.charAt(j);
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if (charsSet.has(char)) {
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max = Math.max(max, charsSet.size);
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while (charsSet.has(char) && i < j) charsSet.delete(s.charAt(i++));
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charsSet.add(char);
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} else charsSet.add(char);
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let l = 0,
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wCount = new Set<string>(),
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maxLen = 0;
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for (const c of s) {
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if (wCount.has(c)) {
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maxLen = Math.max(maxLen, wCount.size);
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while (wCount.has(c)) wCount.delete(s.charAt(l++));
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}
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wCount.add(c);
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}
13-
return Math.max(charsSet.size, max);
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return Math.max(wCount.size, maxLen);
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};
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// TEST CASES

‎ts/src/random/best-time-to-buy-and-sell-stock-ii.ts‎

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// function maxProfit(prices: number[]): number {
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// let profit = 0;
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// for (let i = 1; i < prices.length; i++)
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// if (prices[i] > prices[i - 1]) profit += prices[i] - prices[i - 1];
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// return profit;
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// }
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// console.log(maxProfit([7, 1, 5, 3, 6, 4]));
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// console.log(maxProfit([1, 2, 3, 4, 5]));
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// console.log(maxProfit([7, 6, 4, 3, 1]));
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// console.log(maxProfit([2, 1, 2, 0, 1]));
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function searchInsert(nums: number[], target: number): number {
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let [l, r, m] = [0, nums.length - 1, 0];
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while (l <= r) {
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m = Math.floor((l + r) / 2);
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if (nums[m] < target) l = m + 1;
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else if (nums[m] > target) r = m - 1;
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else if (nums[m] === target) return m;
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}
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return l;
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}
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console.log(searchInsert([1, 3, 5, 6], 5));
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console.log(searchInsert([1, 3, 5, 6], 2));
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console.log(searchInsert([1, 3, 5, 6], 7));

‎ts/src/random/longest-palindromic-substring.ts‎

Lines changed: 39 additions & 0 deletions
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function getMaxPalindrome(l: number, r: number, s: string) {
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while (l >= 0 && r < s.length && s[l] == s[r]) l--, r++;
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return [++l, --r, r - l + 1];
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}
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function longestPalindrome(s: string): string {
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let [maxPalStart, maxPalEnd, maxPalLen, len] = [0, 0, 0, s.length];
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for (let i = 0; i < len; i++) {
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const oddPal = getMaxPalindrome(i, i, s);
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const evenPal = getMaxPalindrome(i, i + 1, s);
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if (oddPal[2] > maxPalLen)
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(maxPalLen = oddPal[2]),
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(maxPalStart = oddPal[0]),
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(maxPalEnd = oddPal[1]);
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if (evenPal[2] > maxPalLen)
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(maxPalLen = evenPal[2]),
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(maxPalStart = evenPal[0]),
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(maxPalEnd = evenPal[1]);
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}
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return s.slice(maxPalStart, maxPalEnd + 1);
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}
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console.log(longestPalindrome('babad'), ' === bab/aba');
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console.log(longestPalindrome('cbbd'), ' === bb');
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// let [l, r, currLen] = [i, i, 0];
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// while (l >= 0 && r < len && s[l] == s[r]) {
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// currLen = r - l + 1;
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// if (currLen > maxPalLen)
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// (maxPalLen = currLen), (maxPalStart = l), (maxPalEnd = r);
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// l--, r++;
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// }
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// (l = i), (r = i + 1);
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// while (l >= 0 && r < len && s[l] == s[r]) {
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// currLen = r - l + 1;
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// if (currLen > maxPalLen)
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// (maxPalLen = currLen), (maxPalStart = l), (maxPalEnd = r);
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// l--, r++;
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// }

‎ts/src/random/palindrome-number.ts‎

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// function isPalindrome(x: number): boolean {
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// if (x < 0) return false;
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// while (x > 9) {
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// const m = Math.pow(10, Math.floor(Math.log10(x)));
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// if (Math.floor(x / m) !== x % 10) return false;
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// x = x % m;
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// x = Math.floor(x / 10);
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// }
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// return true;
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// }
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function isPalindrome(x: number): boolean {
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if (x < 0) return false;
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let [temp, reversed] = [x, 0];
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while (temp > 0)
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(reversed += temp % 10), (reversed *= 10), (temp = Math.floor(temp / 10));
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return reversed === x * 10;
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}
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console.log(isPalindrome(121), ' == true');
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console.log(isPalindrome(-121), ' == false');
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console.log(isPalindrome(10), ' == false');
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console.log(isPalindrome(1221), ' == true');
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console.log(isPalindrome(1000021), ' == false'); // edge case

‎ts/src/random/reverse-prefix-of-word.ts‎

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function reversePrefix(word: string, ch: string): string {
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let i = word.indexOf(ch);
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if (i == -1) return word;
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const res = word.split('');
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let l = 0;
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while (l < i) ([res[l], res[i]] = [res[i], res[l]]), l++, i--;
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return res.join('');
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}
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console.log(reversePrefix('abcdefd', 'd'), ' == dcbaefd');

‎ts/src/random/string-to-integer-atoi.ts‎

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function myAtoi(s: string): number {
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let [l, isPositive, sum, currInt] = [0, true, 0, 0];
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while (s[l] === ' ') l++;
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if (s[l] === '-') isPositive = false;
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if (['+', '-'].includes(s[l])) l++;
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while (s[l] === '0') l++;
7+
while (l < s.length) {
8+
currInt = s.charCodeAt(l);
9+
if (currInt < 48 || currInt > 57) break;
10+
sum += parseInt(s[l]);
11+
sum *= 10;
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l++;
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}
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sum /= 10;
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return isPositive
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? Math.min(Math.pow(2, 31) - 1, sum)
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: Math.max(Math.pow(-2, 31), -sum);
18+
}
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20+
console.log(myAtoi('42'), ' == 42');
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console.log(myAtoi(' -042'), ' == -42');
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console.log(myAtoi('1337c0d3'), ' == 1337');
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console.log(myAtoi('0-1'), ' == 0');
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console.log(myAtoi('words and 987'), ' == 0');
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console.log(myAtoi('+1'), ' == 1');
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console.log(myAtoi('21474836460'), ' == 2147483647');

‎ts/src/random/substring-with-concatenation-of-all-words.ts‎

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1+
function findSubstring(s: string, words: string[]): number[] {
2+
if (!words.length || !words[0].length) return [];
3+
const [firstLetterMap, res, wordLen, allWordLen] = [
4+
new Map<string, number>(words.map((word, i) => [word[0], i])),
5+
[] as number[],
6+
words[0].length,
7+
words[0].length * words.length,
8+
];
9+
for (let i = 0; i < s.length; i++) {
10+
const c = s[i];
11+
if (firstLetterMap.has(c)) {
12+
let [l, r] = [i, i - 1 + allWordLen];
13+
}
14+
}
15+
return [];
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}
17+
18+
findSubstring('', ['bar', 'foo', 'the']);

‎ts/src/random/zigzag-conversion.ts‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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1+
function convert(s: string, numRows: number): string {
2+
if (numRows === 1 || numRows >= s.length) return s;
3+
4+
// Create an array of empty strings for each row
5+
let rows = new Array(numRows).fill('').map(() => '');
6+
7+
let curRow = 0;
8+
let goingDown = false;
9+
10+
// Iterate over each character in the string
11+
for (let char of s) {
12+
rows[curRow] += char;
13+
if (curRow === 0 || curRow === numRows - 1) goingDown = !goingDown; // Reverse direction
14+
curRow += goingDown ? 1 : -1;
15+
}
16+
17+
// Join all rows to get the final string
18+
console.log(rows);
19+
return rows.join('');
20+
}
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22+
console.log(convert('PAYPALISHIRING', 3));

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