Pattern visualizer

Find Peak Element

Comparing mid to its right neighbor reveals which direction is 'uphill': if the array is rising, a peak MUST exist somewhere further right (the sequence can't rise forever, and even a final rise to the array's edge counts as a peak). If it's falling, a peak must exist at mid or to its left. Either way, half the array can be safely discarded every step — no need to scan for the true global maximum, just any local peak. Animated on: nums = [1,2,3,1] — return the index of any peak element (strictly greater than both neighbors)..

Walk uphill: binary search on slope direction

time O(log n)space O(1)step 1 / 6

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A peak is any element strictly greater than both neighbors (edges compare against -infinity). Binary search works because you can always walk UPHILL toward a peak — you never need to check every element.

Pseudocode

1FUNCTION findPeakElement(nums):
2  low = 0, high = the length of nums - 1
3  WHILE low < high:
4    mid = (low + high) / 2, rounded down
5    IF nums[mid] < nums[mid+1]:
6      low = mid + 1   (rising, peak is to the right)
7    ELSE:
8      high = mid   (falling, peak is here or to the left)
9  RETURN low

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