problem287

README

< Previous 　　　　　　　　　　　　　　　　 Next >

287. Find the Duplicate Number (Medium)

Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive.

There is only one repeated number in nums, return this repeated number.

 

Example 1:

Input: nums = [1,3,4,2,2]
Output: 2

Example 2:

Input: nums = [3,1,3,4,2]
Output: 3

Example 3:

Input: nums = [1,1]
Output: 1

Example 4:

Input: nums = [1,1,2]
Output: 1

 

Constraints:

• 2 <= n <= 3 * 104
• nums.length == n + 1
• 1 <= nums[i] <= n
• All the integers in nums appear only once except for precisely one integer which appears two or more times.

 

Follow up:

• How can we prove that at least one duplicate number must exist in nums?
• Can you solve the problem without modifying the array nums?
• Can you solve the problem using only constant, O(1) extra space?
• Can you solve the problem with runtime complexity less than O(n2)?

Related Topics

[Array] [Two Pointers] [Binary Search]

Similar Questions

1. First Missing Positive (Hard)
2. Single Number (Easy)
3. Linked List Cycle II (Medium)
4. Missing Number (Easy)
5. Set Mismatch (Easy)