The answer
It is a classic problem where two sorted arrays are merged in-place into the first array by iterating backwards from the largest elements to the smallest.
Iterating Backwards: A Common Interview Pattern
What is the 'Merge Sorted Array' pattern?
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Initialize the counter to the last index (length - 1), set the condition to run while the counter is greater than or equal to 0, and use decrement (i--).
When you delete an element, the elements to its right shift left. If you iterate left-to-right, you skip elements. Iterating backwards avoids this shifting index bug.
No, traversing an array from right to left takes the exact same O(N) time and hardware cycles as traversing it from left to right.
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