LeetCode in Kotlin

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.

You must solve the problem without modifying the array nums and uses only constant extra space.

Example 1:

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

Output: 2

Example 2:

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

Output: 3

Constraints:

• 1 <= n <= 105
• 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 in linear runtime complexity?

Solution

class Solution {
    fun findDuplicate(nums: IntArray): Int {
        val arr = IntArray(nums.size + 1)
        for (num in nums) {
            arr[num] += 1
            if (arr[num] == 2) {
                return num
            }
        }
        return 0
    }
}

This site is open source. Improve this page.