Function moveFast

javascript/0287-find-the-duplicate-number.js:253–266

(nums, start = 0)

};

const moveFast = (nums, start = 0) => {
    let [slow, fast] = [nums[start], nums[nums[start]]];

    const isSame = () => slow === fast;
    while (!isSame()) {
        /* Time O(N) */
        slow = nums[slow];
        fast = nums[nums[fast]];
    }

    fast = start;

    return [slow, fast];
};

const moveSlow = (nums, slow, fast) => {
    const isSame = () => slow === fast;