# Problem: Sum numbers 1 to N # Pseudocode: total = 0; for each i from 1 to N, add i to total def sum_to_n(n): total = 0 for i in range(1, n+1): total += i return total (Conditionals) When to use: Different actions based on data. Python tool: if / elif / else
for i in range(1, 101): if i % 15 == 0: print("FizzBuzz") elif i % 3 == 0: print("Fizz") elif i % 5 == 0: print("Buzz") else: print(i) Check if a word reads the same backward. think like a programmer python edition pdf
def fibonacci(n): a, b = 0, 1 for _ in range(n): print(a, end=" ") a, b = b, a + b | Mistake | How to Think | Python Fix | |---------|--------------|-------------| | Off‑by‑one | “Is my last iteration correct?” | Check range(start, stop) – stop is exclusive. | | Variable not defined | “Where was this variable created?” | Define before use. | | Wrong output | “Add print statements to see intermediate values.” | Use print() or debugger ( pdb ). | # Problem: Sum numbers 1 to N #
| Step | Action | Python Example Thinking | |------|--------|--------------------------| | 1 | the problem | “What are the inputs? Outputs? Constraints?” | | 2 | Plan without code | Write steps in plain English (pseudocode). | | 3 | Implement in Python | Translate pseudocode to Python. | | 4 | Test & Debug | Run with sample inputs, fix errors. | 2. Core Programming Patterns (with Python) Pattern A: Repetition (Loops) When to use: Doing the same action many times. Python tool: for , while | | Variable not defined | “Where was