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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[BUG]: Biased shuffle implementation in bogoSort (incorrect Fisher–Yates range)","articleBody":"### Description\n\nThe current `shuffle` function used by the `bogoSort` implementation appears to implement a biased version of the Fisher–Yates shuffle.\n\nSpecifically, the random index is selected from an incorrect range, which prevents some permutations from ever occurring. This results in a non-uniform shuffle and may affect the theoretical correctness of randomized algorithms such as `bogoSort`.\n\n### Expected Behavior\n\nThe shuffle function should implement an unbiased Fisher–Yates algorithm, where each permutation of the array is equally likely.\n\nThis requires selecting the random index from the inclusive range [0, i] during each iteration.\n\n### Actual Behavior\n\nThe current implementation selects the random index from ` [0, i) `, which introduces bias and makes some permutations impossible.\n\nAs a result:\n\n- The shuffle is not uniform\n- The sorted permutation may be unreachable for certain inputs\n- The expected probabilistic behaviour of `bogoSort` is violated\n\n### Steps to reproduce (if applicable)\n\n1. Use the current shuffle implementation\n2. Shuffle a small array (e.g. [1, 2, 3]) many times\n3. Count permutation frequencies\n4. Observe that some permutations never appear or appear significantly less often\n\n### Additional information\n\n#### Suggested fix\n\nUpdate the shuffle to use the standard Fisher–Yates algorithm:\n\n```js\nfunction shuffle(array) {\n  for (let i = array.length - 1; i \u003e 0; i--) {\n    const j = Math.floor(Math.random() * (i + 1));\n    [array[i], array[j]] = [array[j], array[i]];\n  }\n}\n```","author":{"url":"https://github.com/Ayoub-FG","@type":"Person","name":"Ayoub-FG"},"datePublished":"2025-12-23T19:42:37.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":2},"url":"https://github.com/1867/JavaScript/issues/1867"}