First Duplicate Value Index

Given an integer array, return the first index where the current value has already appeared earlier in the array. If no duplicate exists, return -1.

Inputnums = [2, 1, 3, 5, 3, 2]Output4WhyThe value `3` repeats first at index `4`.

Inputnums = [1, 2, 3, 4]Output-1WhyAll values are unique.

Problem

Given an integer array, return the first index where the current value has already appeared earlier in the array. If no duplicate exists, return -1.

Examples

Example 1

Inputnums = [2, 1, 3, 5, 3, 2]Output4WhyThe value `3` repeats first at index `4`.

Example 2

Inputnums = [1, 2, 3, 4]Output-1WhyAll values are unique.

Constraints

`1 <= len(nums) <= 10^5`
`-10^9 <= nums[i] <= 10^9`
Need the earliest duplicate index, not just any duplicate value

Problem

Given an integer array, return the first index where the current value has already appeared earlier in the array. If no duplicate exists, return -1.

Examples

Example 1

Inputnums = [2, 1, 3, 5, 3, 2]Output4WhyThe value `3` repeats first at index `4`.

Example 2

Inputnums = [1, 2, 3, 4]Output-1WhyAll values are unique.

Constraints

`1 <= len(nums) <= 10^5`
`-10^9 <= nums[i] <= 10^9`
Need the earliest duplicate index, not just any duplicate value

Problem

Given an integer array, return the first index where the current value has already appeared earlier in the array. If no duplicate exists, return -1.

Examples

Example 1

Inputnums = [2, 1, 3, 5, 3, 2]Output4WhyThe value `3` repeats first at index `4`.

Example 2

Inputnums = [1, 2, 3, 4]Output-1WhyAll values are unique.

Constraints

`1 <= len(nums) <= 10^5`
`-10^9 <= nums[i] <= 10^9`
Need the earliest duplicate index, not just any duplicate value

Interview Guides

Problem

Examples

Constraints

Problem

Examples

Constraints

First Duplicate Value Index

Problem

Examples

Constraints

Problem

Examples

Constraints