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Leetcode 127, "Word Ladder" with Promises as a queue
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| /* https://leetcode.com/problems/word-ladder/ */ | |
| const checkAdjacency = (a, b) => { | |
| if (a.length !== b.length) { | |
| return false; | |
| } | |
| let first = true; | |
| for (let i = 0; i < a.length; i++) { | |
| if (a[i] !== b[i]) { | |
| if (first) first = false; | |
| else return false; | |
| } | |
| } | |
| return true; | |
| }; | |
| function ladderLength(beginWord, endWord, wordList) { | |
| wordList.push(beginWord); | |
| const adjacency = []; | |
| for (let i = 0; i < wordList.length; i++) { | |
| adjacency[i] ||= Array(i).fill(0); | |
| for (let j = 0; j < i; j++) { | |
| adjacency[i][j] = checkAdjacency(wordList[i], wordList[j]); | |
| } | |
| } | |
| let min = Infinity; | |
| const visited = Array(wordList.length).fill(false); | |
| const findAdjacent = (i, s) => { | |
| if (wordList[i] === endWord) min = Math.min(min, s); | |
| for (let j = 0; j < wordList.length; j++) { | |
| const isAdj = j < i ? adjacency[i][j] : adjacency[j][i]; | |
| if (isAdj && !visited[j]) { | |
| visited[j] = true; | |
| // Sync promise execution is just a queue | |
| new Promise((res) => res(findAdjacent(j, s + 1))); | |
| } | |
| } | |
| }; | |
| findAdjacent(wordList.length - 1, 0); | |
| return new Promise((res) => res(min === Infinity ? 0 : min)); | |
| } | |
| console.log( | |
| await ladderLength("hit", "cog", ["hot", "dot", "dog", "lot", "log", "cog"]) | |
| ); | |
| // 5 |
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