CT_Prerequisites_Comprehensive

CT: Comprehensive Prerequisites Guide

IMPORTANT

Goal: CT doesn’t need advanced math. It needs Logic and Attention to Detail.

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1. Logic Basics

1.1 True vs False

• True: Yes, Correct, On.
• False: No, Incorrect, Off.
• Comparison:
  • $5>3$ is True.
  • $5==3$ is False.

1.2 Logical Operators

1. AND: Both must be True.
   • “I will go IF it is sunny AND I have money.”
2. OR: At least one must be True.
   • “I will eat IF it is Pizza OR Burger.”
3. NOT: Opposite.
   • “NOT True” is False.

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2. Arithmetic Basics

2.1 Operations

• Add/Sub/Mul: $+$, $-$, $\ast$.
• Division: /. (e.g., $10/2=5$).
• Modulus ($\%$): The Remainder.
  • $10\%3=1$ (Because $10=3\times 3+1$).
  • Use Case: Checking Even/Odd ($x\%2==0$).

2.2 Precedence (BODMAS)

1. Brackets.
2. Orders (Powers).
3. Division / Multiplication (Left to Right).
4. Addition / Subtraction (Left to Right).

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3. The “State” Concept

• Variable State: A variable has one value at any specific moment.
• History: It doesn’t remember what it was 5 minutes ago.
• Overwrite: A = 5, then A = 10. The 5 is gone forever.

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4. Common Pitfalls

1. Assignment vs Equality:
   • A = 10 (Action: Make A 10).
   • A == 10 (Question: Is A 10?).
2. Infinite Loops:
   • Forgetting to update the variable in a while loop.
3. Off-by-One:
   • Lists start at Index 0.
   • The last item is at Index Length - 1.