JavaEasyNumbers10 min
Compute a factorial with BigInteger
Print n factorial as an exact decimal integer. Follow the stated ordering and edge-case conventions exactly. Interviewers use this task to probe algorithm selection, invariants, and boundary handling.
Input
One integer n.
Output
Print n factorial as an exact decimal integer.
Constraints
0 <= n <= 1000.
Example
Input
5
Output
120
Example 2 input
100
Output
93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
This example exercises exact arithmetic beyond primitive integer capacity.
Public test cases (2)
Input
5
Expected output
120
Input
10
Expected output
3628800
Hints (2)
- Identify the state needed to avoid recomputing work for each element.
- Multiply the integers from 2 through n using BigInteger to avoid overflow.
Target complexity: time O(n) multiplications · space O(n log n) bits