## Problem:

given m<n, generate random numbers of m within range(0..n).


## Solutions:

• ### a Knuth’s solution of O(log n) time :

But when n was large, it meets bootleneck. Improve with:

f

## Principles

talk to user

### Specify an Abstract Problem

get a clean, crisp problem statement.

### Explore the Desgn Space

think for a day and code for a min rather than per contra

choose the best

### Retrospect

Polya’s delightful How to Solve It can help programmer become a better problem solver.