Definition
O(1) is "Constant Time", where you know the location or can calculate it, finishing instantly regardless of N.
Key Characteristics
- ✓Jump directly to address
- ✓1 Billion items? Still 1 step
Use Cases
Used in these scenarios:
📍
Array Index Access
arr[5] accesses instantly with one address calculation
🔑
Hash Table Lookup
HashMap.get() jumps directly via hash
📚
Stack Push/Pop
Only touches the top, always O(1)
🚶
Queue Operations
Only touches front/back ends
Complexity
Time Complexity
Best
O(1)
Average
O(1)
Worst
O(1)
Space Complexity
O(1)
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