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/**
 * @param {number[]} cost
 * @return {number}
 */
var minCostClimbingStairs = function(cost) {
    // recursive traverse array
    cost.unshift(0, 0)
    for (var step = 2; step < cost.length; step++) {
        // recalculate min cost
        cost[step] += Math.min(cost[step - 1], cost[step - 2])

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/**
 * @param {number} n
 * @return {number}
 */
var climbStairs = function(n) {
    if (n <= 3) {
        return n;
    }

    let prev = 2;

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/**
 * @param {string} beginWord
 * @param {string} endWord
 * @param {string[]} wordList
 * @return {number}
 */
var ladderLength = function(beginWord, endWord, wordList) {
    // edge case
    if(wordList.indexOf(endWord) === -1) {
        return 0

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/**
 * @param {number} n
 * @param {number[][]} edges
 * @return {boolean}
 */
var validTree = function(n, edges) {
    if (!n) {
        return true;
    }

markbrutx

class UnionFind {
    constructor() {
        this.parent = {}
    }

    findParent(x) {
        if (this.parent[x] === undefined) {
            this.parent[x] = x
        }

markbrutx

/**
 * @param {number[][]} edges
 * @return {number[]}
 */
var findRedundantConnection = function(edges) {
    const parrents = Array.from({
        length: edges.length + 1
    }, (v, i) => i)

    const ranks = Array.from({

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/**
 * @param {number} numCourses
 * @param {number[][]} prerequisites
 * @return {number[]}
 */
var findOrder = function(numCourses, prerequisites) {
    let crsPre = {}

    for(let i = 0; i< numCourses; i++){
        crsPre[i] = []

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/**
 * @param {number} numCourses
 * @param {number[][]} prerequisites
 * @return {boolean}
 */
var canFinish = function(numCourses, prerequisites) {
    
    const preMap = new Array(numCourses).fill(0).map(()=>[])
    for(let i = 0; i < prerequisites.length; i++) {
        let [crs, pre] = prerequisites[i]

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/**
 * @param {number[][]} rooms
 * @return {void} Do not return anything, modify rooms in-place instead.
 */
var wallsAndGates = function(rooms) {
    if(!rooms || rooms.length === 0) {
        return;
    }

    let ROWS = rooms.length;

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/**
 * @param {number[][]} grid
 * @return {number}
 */
var orangesRotting = function(grid) {
    // counter for 
    let time = 0;
    let fresh = 0; // how many fresh oranges
    let rotten = [] // cords of rotten oranges