Given an arrayContinue reading “[Leetcode]287. Find the Duplicate Number”numscontainingn+ 1 integers where each integer is between 1 andn(inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.Example 1:Input:`[1,3,4,2,2]`

Output:2Note:1. Youmust notmodify the array (assume the array is read only). 2. You must use only constant,O(1) extra space. 3. Your runtime complexity should be less thanO(n^{2}). 4. There is only one duplicate number in the array, but it could be repeated more than once.

## Floyd’s Cycle Detection Algorithm – [Leetcode]142. Linked List Cycle II

The cycle detection problem is to find the cycle in a sequence, and Floyd’s cycle detection algorithm, aka Tortoise and Hare algorithm, is a two pointers algorithm to detect the cycle and the start of the cycle as well.

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