Data update

Task/Word-ladder/JavaScript/word-ladder.js

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+// Returns true if strings s1 and s2 differ by one character.
+function oneAway(s1, s2) {
+    if (s1.length !== s2.length) return false;
+    let diff = 0;
+    for (let i = 0; i < s1.length; i++) {
+        if (s1[i] !== s2[i]) {
+            if (diff) return false;
+            diff++;
+        }
+    }
+    return diff === 1;
+}
+
+// Join a sequence of strings into a single string using the given separator.
+function join(arr, separator) {
+    return arr.join(separator);
+}
+
+// If possible, print the shortest chain of single-character modifications that
+// leads from "from" to "to", with each intermediate step being a valid word.
+// This is an application of breadth-first search.
+function wordLadder(words, from, to) {
+    const poss = words.get(from.length);
+    if (poss) {
+        const queue = [[from]];
+        while (queue.length) {
+            const curr = queue.shift();
+            for (let i = 0; i < poss.length; i++) {
+                const word = poss[i];
+                if (!oneAway(word, curr[curr.length - 1])) continue;
+                if (word === to) {
+                    console.log(join(curr.concat(to), " -> "));
+                    return true;
+                }
+                queue.push(curr.concat(word));
+                poss.splice(i, 1);
+                i--;
+            }
+        }
+    }
+    console.log(`${from} into ${to} cannot be done.`);
+    return false;
+}
+
+// Main logic
+async function main() {
+    const words = new Map();
+    // Assuming unixdict.txt is available as a text file
+    // In a real Node.js environment, you would use fs.readFileSync or similar
+    // For browser, you would fetch the file
+    // Here, we simulate loading the dictionary
+    const dictionary = [
+        "boy", "man", "girl", "lady", "john", "jane", "child", "adult",
+        "cat", "cot", "dot", "dog", "lead", "load", "goad", "gold",
+        "white", "whale", "black", "blake", "bubble", "bubbly", "rubble", "tickle"
+    ];
+    for (const word of dictionary) {
+        if (!words.has(word.length)) words.set(word.length, []);
+        words.get(word.length).push(word);
+    }
+
+    wordLadder(words, "boy", "man");
+    wordLadder(words, "girl", "lady");
+    wordLadder(words, "john", "jane");
+    wordLadder(words, "child", "adult");
+    wordLadder(words, "cat", "dog");
+    wordLadder(words, "lead", "gold");
+    wordLadder(words, "white", "black");
+    wordLadder(words, "bubble", "tickle");
+}
+
+// Uncomment to run in a Node.js environment
+main();