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Time Complexity
Last Updated : 26 May, 2026
title: Time Complexity
DSA in Java147 words8 headingsTables includedExamples included
title: Time Complexity description: Big O notation aur algorithm analysis
Algorithm kitna time leta hai — input size ke saath kaise grow karta hai.
Big O Notation
| Notation | Name | Example |
|---|---|---|
| O(1) | Constant | Array index access |
| O(log n) | Logarithmic | Binary search |
| O(n) | Linear | Linear search |
| O(n log n) | Linearithmic | Merge sort |
| O(n²) | Quadratic | Bubble sort |
| O(2ⁿ) | Exponential | Fibonacci recursive |
| O(n!) | Factorial | Permutations |
Best → Worst: O(1) < O(log n) < O(n) < O(n log n) < O(n²) < O(2ⁿ) < O(n!)
Examples
O(1) — Constant
int getFirst(int[] arr) { return arr[0]; }
O(n) — Linear
java exampleWoHoTech
int sum(int[] arr) {
int s = 0;
for (int n : arr) s += n; // n iterations
return s;
}O(n²) — Quadratic
void bubbleSort(int[] arr) {
for (int i = 0; i < arr.length; i++) // n
for (int j = 0; j < arr.length-i-1; j++) // n
if (arr[j] > arr[j+1]) { /* swap */ }
// Total: n × n = n²
}
O(log n) — Logarithmic
int binarySearch(int[] arr, int target) {
int lo = 0, hi = arr.length - 1;
while (lo <= hi) {
int mid = lo + (hi - lo) / 2;
if (arr[mid] == target) return mid;
else if (arr[mid] < target) lo = mid + 1;
else hi = mid - 1;
}
return -1; // Each iteration halves the search space
}
Space Complexity
Algorithm kitna extra memory use karta hai.
- O(1): Constant extra space (in-place)
- O(n): Input size ke proportional extra space
- O(log n): Recursive call stack (binary search recursion)
Exam Focus
Revise definitions, diagrams, examples, and short-answer points for Time Complexity.
Interview Use
Prepare one clear explanation, one practical example, and one common mistake for this Java topic.
Search Terms
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