Week 1 — introduction to algorithms

Quiz 2 scope: Weeks 1–8 per IITM May 2026 foundation courses. Source baseline: IITM BS admissions important-dates calendar · May 2026 cycle. Times on assessments are operational conventions — verify hall ticket.

Week map

Classify → Represent → Execute → Trap-check

• Recognize: Ask: What is stored after x = 3 then x = x + 2?
• Procedure: Execute assignments top to bottom without skipping. When a variable is reassigned, old value is lost. For expressions, apply operator precedence before assignment.
• Variations / traps: Watch for: Using = for comparison instead of ==.

Formula chain (compressed)

Trace types → evaluate expressions with precedence → assignment updates bindings.

1. Types — int, float, str, bool — before any operator
2. Precedence — **, *, /, //, %, +, - — mixed arithmetic
3. Division — / → float, // → floor — Python 3
4. Assignment — name = expression — RHS fully evaluated first
5. Comparison — ==, !=, <, chained: a<b<c — yields bool

Deep study

Programming in Python · Week 1 — Algorithms and types

Week map

Type notation

• int → integer type → whole numbers → 17, -4, 0.
• float → floating type → decimal approximations → 3.0, -0.25, 2.718.
• bool → boolean type → truth values → True, False only.
• str → string type → text sequence → "score", 'A'.
• type(x) → returns type of value → type(3/2) is float in Python 3.

Literals and assignment

• x = 5 → assignment statement → bind name x to value 5 → later x reads 5 until reassigned.
• = is not equality test; equality is ==.

python
Run Inline
a = 10
b = a + 3
a = 2
print(b)

Expressions and operators

Algorithm tracing habit

python
Run Inline
x = 4
y = x * 2
x = y - 1
print(x + y)

Pattern families

Easy — Final value prediction

• Straight-line assignments without branches.
• Single print of expression or variable.
• Identify type of literal or simple expression.

Medium — Mixed-type expressions

• Division always float in Python 3.
• Floor division and mod with negatives (know course convention; often positive mod for quiz).
• String + vs numeric + — types must match for numeric add.

Hard — Multi-variable dependency chains

• Reassignment overwrites; old value gone unless another name still references it (week 1 usually one name per value).
• Expression on RHS fully evaluated before LHS update.
• print with comma-separated items vs concatenation.

Worked mini-examples

python
Run Inline
a = 9 / 2      # 4.5 float
b = 9 // 2     # 4 int
c = 9 % 2      # 1

python
Run Inline
n = 7
msg = "Level " + str(n)   # "Level 7"
# "Level " + n  would error

python
Run Inline
result = 10 - 2 ** 3 + 1   # 10 - 8 + 1 = 3

python
Run Inline
p = 1
q = p + 4    # q = 5
p = q        # p = 5
q = p + 2    # q = 7
# p is 5, q is 7

Traps

• Using = in a condition (week 2 topic, but appears early in distractors).
• Assuming / gives integer quotient in Python 3.
• Concatenating str with int without str().
• Reading code bottom-up when state evolves top-down.
• Confusing // with /.

Diagnostic (try yourself)

1. What is printed?

python
Run Inline
x = 8
y = x // 3
x = y * 5
print(x)

1. What is the type of 3 + 2.0? What is the type of 4 / 2?
2. What is the value of 10 - 3 ** 2 + 1?
3. After a = 6, b = a, a = 10, what are a and b?
4. Write one expression that produces "Go" + "Go" using only the integer 2 and string operations (no quotes in the expression except on "Go").

ChatGPT prep archive

• Chatty reference archive

Archived import for extra depth — complements the notes above, not official IITM material.

Core concepts

• Algorithm: ordered steps that transform input to output; state is values in memory at each step.
• Types: int, float, bool, str; type tells which operations are legal.
• Expressions evaluate to a value; statements change state (assignment).
• Tracing: follow line order; update variables; print shows current value.

Notation & vocabulary

Pattern families

Easy — Predict final value

Medium — Type of expression

Hard — Trace with dependencies

Drill these on the pattern atlas — filter to week 1.

Traps

• Using = for comparison instead of ==.
• Assuming / returns int in Python 3.
• Reading code bottom-up when state evolves top-down.
• Ignoring that strings concatenate with +, not add numerically.

Retrieval prompts

1. What is stored after x = 3 then x = x + 2?
2. What type is 3 / 2 in Python 3?
3. Difference between expression and statement?

Practice loop

1. Read Deep study (if present) or core concepts once.
2. Recite the formula chain without looking.
3. Open one easy pattern on the interactive atlas for week 1.
4. Attempt without solutions; mark studied after an honest try.
5. Say one trap aloud before closing the tab.

Related

• Full weeks 1–8 prep guide
• Pattern atlas note
• Formula chain desk