Time complexity measures how execution time grows relative to input size n.

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Complexity	Meaning	Example
O(1)	Constant time, doesn’t depend on input size	Access array element
O(log n)	Input halves each step	Binary Search
O(n)	Runs once per element	Linear search
O(n log n)	Divide and merge type algorithms	Merge Sort, Quick Sort
O(n²)	Nested loops	Bubble Sort
O(2ⁿ)	Exponential growth	Recursive subsets

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