Solution

Method 1 – Greedy Simulation

Intuition

We want to mark all indices in nums as soon as possible. Since we can only mark an index when its value is zero at the second specified by changeIndices, we need to optimally decrement values so that all indices reach zero at the right time. We simulate the process, always decrementing the largest nonzero values first, and try all possible seconds to see if it's possible to mark all indices by that time.

Approach

Use binary search on the answer: the earliest second in [1, m] where all indices can be marked.
For each candidate second t, simulate the process:
- For each index, find the last second ≤ t when it can be marked (i.e., when changeIndices[s] == i for some s ≤ t).
- For each index, count how many decrements are needed before its mark time.
- If the total number of decrements needed is ≤ the number of available operations (t - n), it's possible.
Return the minimum such t</

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