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Created javascript solutions for 20 problems#363

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Merged
neetcode-gh merged 20 commits intoneetcode-gh:mainfromloczek:main
Jul 6, 2022
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c23d249
add 2-add-two-numbers
loczekJul 6, 2022
1f592b3
add 5-Longest-Palindromic-Substring
loczekJul 6, 2022
a6ffd6f
add 17-Letter-Combinations-of-a-Phone-Number
loczekJul 6, 2022
bde7f31
add 22-Generate-Parentheses
loczekJul 6, 2022
ebc7d7a
add 44-Permutations
loczekJul 6, 2022
91ce4eb
add 62-Unique-Paths
loczekJul 6, 2022
95c87ff
add 78-Subsets
loczekJul 6, 2022
11f7f0d
add 91-Decode-Ways
loczekJul 6, 2022
a0769b0
add 105-Construct-Binary-Tree-from-Preorder-and-Inorder-Traversal
loczekJul 6, 2022
a09546f
add 131-Palindrome-Partitioning
loczekJul 6, 2022
c61789b
add 198-House-Robber
loczekJul 6, 2022
955dc86
add 202-Happy-Number
loczekJul 6, 2022
1b59ccb
add 208-Implement-Trie
loczekJul 6, 2022
8c2b30a
add 211-Design-Add-and-Search-Words-Data-Structure
loczekJul 6, 2022
9b78240
add 230-Kth-Smallest-Element-in-a-BST
loczekJul 6, 2022
61e70a5
add 287-Find-the-Duplicate-Number
loczekJul 6, 2022
d093d65
add 647-Palindromic-Substrings
loczekJul 6, 2022
de3a58e
add 746-Min-Cost-Climbing-Stairs
loczekJul 6, 2022
83b7926
add 853-Car-Fleet
loczekJul 6, 2022
7256e8c
add 1448-Count-Good-Nodes-in-Binary-Tree
loczekJul 6, 2022
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
function buildTree(preorder, inorder) {
if (!preorder.length || !inorder.length) return null;

let root = new TreeNode(preorder[0]);
let mid = inorder.indexOf(preorder[0]);

root.left = buildTree(preorder.slice(1, mid + 1), inorder.slice(0, mid));
root.right = buildTree(preorder.slice(mid + 1), inorder.slice(mid + 1));
return root;
}
33 changes: 33 additions & 0 deletionsjavascript/131-Palindrome-Partitioning.js
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function partition(s) {
let res = [];
let part = [];

function dfs(i) {
if (i >= s.length) {
res.push(part.slice());
return;
}

for (let j = i; j < s.length; j++) {
if (isPali(s, i, j)) {
part.push(s.slice(i, j + 1));
dfs(j + 1);
part.pop();
}
}
}

dfs(0);
return res;

function isPali(s, l, r) {
while (l < r) {
if (s[l] != s[r]) {
return false;
}
l = l + 1;
r = r - 1;
}
return true;
}
}
20 changes: 20 additions & 0 deletionsjavascript/1448-Count-Good-Nodes-in-Binary-Tree.js
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function goodNodes(root) {
let total = 0;

function traverse(node, prev) {
if (!node) return;

if (node.left || node.right) {
traverse(node.left, Math.max(node.val, prev));
traverse(node.right, Math.max(node.val, prev));
}

if (node.val >= prev) {
total += 1;
}
}

traverse(root, root.val);

return total;
}
31 changes: 31 additions & 0 deletionsjavascript/17-Letter-Combinations-of-a-Phone-Number.js
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function letterCombinations(digits) {
let res = [];

const digitToChar = {
2: "abc",
3: "def",
4: "ghi",
5: "jkl",
6: "mno",
7: "qprs",
8: "tuv",
9: "wxyz",
};

function backtrack(i, curStr) {
if (curStr.length === digits.length) {
res.push(curStr);
return;
}

for (const c of digitToChar[digits[i]]) {
backtrack(i + 1, curStr + c);
}
}

if (digits) {
backtrack(0, "");
}

return res;
}
12 changes: 12 additions & 0 deletionsjavascript/198-House-Robber.js
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function rob(nums) {
let rob1 = 0;
let rob2 = 0;

for (const n of nums) {
let temp = Math.max(n + rob1, rob2);
rob1 = rob2;
rob2 = temp;
}

return rob2;
}
27 changes: 27 additions & 0 deletionsjavascript/2-Add-Two-Numbers.js
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function addTwoNumbers(l1, l2) {
let temp1 = l1;
let temp2 = l2;

let dummy = new ListNode(0);
let merged = dummy;

let carry = 0;

while (temp1 || temp2) {
let sum = (temp1?.val || 0) + (temp2?.val || 0) + carry;
carry = Math.floor(sum / 10);
sum = sum % 10;

merged.next = new ListNode(sum);
merged = merged.next;

if (temp1) temp1 = temp1?.next;
if (temp2) temp2 = temp2?.next;
}

if (carry > 0) {
merged.next = new ListNode(carry);
}

return dummy.next;
}
25 changes: 25 additions & 0 deletionsjavascript/202-Happy-Number.js
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function isHappy(n) {
const visit = new Set();

while (!visit.has(n)) {
visit.add(n);
n = sumOfSquares(n);

if (n == 1) return true;
}

return false;
}

function sumOfSquares(n) {
let output = 0;

while (n) {
let digit = n % 10;
digit = digit ** 2;
output += digit;
n = Math.floor(n / 10);
}

return output;
}
50 changes: 50 additions & 0 deletionsjavascript/208-Implement-Trie.js
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class TrieNode {
constructor() {
this.children = {};
this.endOfWord = false;
}
}

class Trie {
constructor() {
this.root = new TrieNode();
}

insert(word) {
let cur = this.root;

for (const c of word) {
if (!(c in cur.children)) {
cur.children[c] = new TrieNode();
}
cur = cur.children[c];
}
cur.endOfWord = true;
}

search(word) {
let cur = this.root;

for (const c of word) {
if (!(c in cur.children)) {
return false;
}
cur = cur.children[c];
}

return cur.endOfWord;
}

startsWith(prefix) {
let cur = this.root;

for (const c of prefix) {
if (!(c in cur.children)) {
return false;
}
cur = cur.children[c];
}

return true;
}
}
55 changes: 55 additions & 0 deletionsjavascript/211-Design-Add-and-Search-Words-Data-Structure.js
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class TrieNode {
constructor() {
this.children = {};
this.endOfWord = false;
}
}

class WordDictionary {
constructor() {
this.root = new TrieNode();
}

addWord(word) {
let cur = this.root;

for (const c of word) {
if (!(c in cur.children)) {
cur.children[c] = new TrieNode();
}
cur = cur.children[c];
}
cur.endOfWord = true;
}

search(word) {
function dfs(j, root) {
let cur = root;

for (let i = j; i < word.length; i++) {
const c = word[i];

if (c === ".") {
for (const key in cur.children) {
if (Object.prototype.hasOwnProperty.call(cur.children, key)) {
const child = cur.children[key];

if (dfs(i + 1, child)) {
return true;
}
}
}
return false;
} else {
if (!(c in cur.children)) {
return false;
}
cur = cur.children[c];
}
}

return cur.endOfWord;
}
return dfs(0, this.root);
}
}
27 changes: 27 additions & 0 deletionsjavascript/22-Generate-Parentheses.js
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function generateParenthesis(n) {
const stack = [];
const res = [];

function backtrack(openN, closedN) {
if (openN === n && closedN === n) {
res.push(stack.join(""));
return;
}

if (openN < n) {
backtrack(openN + 1, closedN);
stack.pop();
stack.push("(");
}

if (closedN < openN) {
backtrack(openN, closedN + 1);
stack.push(")");
stack.pop();
}
}

backtrack(0, 0);

return res;
}
21 changes: 21 additions & 0 deletionsjavascript/230-Kth-Smallest-Element-in-a-BST.js
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function kthSmallest(root, k) {
let n = 0;
const stack = [];
let cur = root;

while (cur || stack) {
while (cur) {
stack.push(cur);
cur = cur.left;
}

cur = stack.pop();
n += 1;

if (n == k) {
return cur.val;
}

cur = cur?.right;
}
}
24 changes: 24 additions & 0 deletionsjavascript/287-Find-the-Duplicate-Number.js
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function findDuplicate(nums) {
let slow = 0;
let fast = 0;

while (true) {
slow = nums[slow];
fast = nums[nums[fast]];
if (slow == fast) {
break;
}
}

let slow2 = 0;

while (true) {
slow = nums[slow];
slow2 = nums[slow2];
if (slow == slow2) {
break;
}
}

return slow;
}
25 changes: 25 additions & 0 deletionsjavascript/46-Permutations.js
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function permute(nums) {
const res = [];

if (nums.length === 1) {
return [nums.slice()];
}

for (const i of nums) {
let n = nums.shift();

let perms = permute(nums);

for (const perm of perms) {
perm.push(n);
}

perms.forEach((perm) => {
res.push(perm);
});

nums.push(n);
}

return res;
}
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