mediumArraysPattern: Mixed
Reconstruct Alternating Sequence Solution
Problem Statement
Given an array of integers `diff` representing the differences between consecutive elements in a reconstructed array, determine the original array that these differences represent, assuming the first element is 0 and differences alternate between being added and subtracted from the running total.
Examples
Example 1:
Input:[1, -2, 3, -4]
Output:[0, 1, -1, 2, -2]
Explanation: Starting with 0, add 1 to get 1, subtract 2 to get -1, add 3 to get 2, subtract 4 to get -2
Example 2:
Input:[5, -3, 2, -1]
Output:[0, 5, 2, 4, 3]
Explanation: Starting with 0, add 5 to get 5, subtract 3 to get 2, add 2 to get 4, subtract 1 to get 3
Constraints
- The length of the differences array will not exceed 10^5 elements.
- All numbers in the differences array are integers between -10^9 and 10^9.
- The input array may be empty, in which case the output is [0].
- The total sum of absolute values of differences will not exceed 10^6.
Time: O(n) Space: O(n)
The optimal approach involves initializing the result array with 0 and then iteratively applying the given differences, switching between addition and subtraction based on the pattern. This results in a linear time complexity.
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