3. Prefix Sum

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Input: nums = [1, 2, 3, 4, 5]

Output: [1, 3, 6, 10, 15]

Explanation: The prefix sum array is calculated as follows: [1, 1+2, 1+2+3, 1+2+3+4, 1+2+3+4+5].

Input: nums = [-1, 0, 2, -3, 1]

Output: [-1, -1, 1, -2, -1]

Explanation: The prefix sum array is calculated as follows: [-1, -1+0, -1+0+2, -1+0+2-3, -1+0+2-3+1].

Input: nums = []

Output: []

Explanation: If the input array is empty, the prefix sum array is also empty.

Time Complexity

O(n)

Space Complexity

O(n)