Exercises · T02 conditions

Covers: boolean expressions, if/else, else if chains, logical operators, short-circuit guards, switch, nested decisions, the conditional operator. Lectures L07–L08. Outcomes PF-4.1–PF-4.4.

13 exercises · ladder 🟢 → 🔴.

PF-E-014 · Pass/Fail

Difficulty: Beginner · Lecture: L07 · Outcomes: PF-4.1 Prerequisites: E-003 Problem: Read a score (integer). Print PASS if it is 60 or more, otherwise FAIL. Input: one integer · Output: one word. Sample: 72 → PASS Hints: >= — 60 itself passes.

PF-E-015 · Adult or Minor

Difficulty: Beginner · Lecture: L07 · Outcomes: PF-4.1 Prerequisites: E-014 Problem: Read an age. Print minor (under 18) or adult. Then print the same decision made with the conditional operator instead of if/else. Input: one integer · Output: one word, printed twice. Sample: 15 → minor / minor Hints: the ?: version assigns the word to a variable, then prints once.

PF-E-016 · Positive/Negative/Zero

Difficulty: Beginner · Lecture: L07 · Outcomes: PF-4.1 Prerequisites: E-015 Problem: Read an integer; classify it as positive, negative, or zero using an if/else if/else chain. Input: one integer · Output: one word. Sample: -9 → negative Hints: test zero first or last — just be consistent.

PF-E-017 · Leap Year

Difficulty: Foundational · Lecture: L07 · Outcomes: PF-4.2 Prerequisites: E-016 Problem: Read a year; print leap or common. Rule: divisible by 4, except centuries not divisible by 400. Input: one integer (year) · Output: one word. Sample: 1900 → common / 2000 → leap / 2024 → leap Hints: nest the century test inside the divisible-by-4 test; test 1900, 2000, 2024, 2023.

PF-E-018 · Triangle Validity + Type

Difficulty: Foundational · Lecture: L07 · Outcomes: PF-4.2 Prerequisites: E-017 Problem: Read three side lengths. First check validity (each side positive; sum of any two greater than the third). If invalid print invalid; otherwise print equilateral, isosceles, or scalene. Input: three doubles · Output: one word. Sample: 3 3 3 → equilateral / 1 2 9 → invalid Hints: validity first, as a guard; the three type tests are mutually exclusive.

PF-E-019 · Grade Point Average Band

Difficulty: Foundational · Lecture: L07 · Outcomes: PF-4.2 Prerequisites: E-016 Problem: Read a GPA (0.0–4.0). Print the band: first (≥ 3.5), two-one (≥ 3.0), two-two (≥ 2.0), pass (≥ 1.0), else fail. Reject values outside 0.0–4.0 with out of range. Input: one double · Output: one word. Sample: 2.9 → two-two / 4.5 → out of range Hints: descending chain — order matters (L07's ordered rule set).

PF-E-020 · Electricity Tariff

Difficulty: Intermediate · Lecture: L07 · Outcomes: PF-4.2, PF-2.1 Prerequisites: E-019 Problem: Read electricity units consumed. First 100 units cost 1.20 each, next 200 cost 1.80 each, all beyond cost 2.50 each; plus a fixed 150 meter fee (charged even at 0 units). Print the total bill with 2 decimals. Input: one integer (units ≥ 0) · Output: one money value. Sample: 350 → 610.00 Hints: split into bands with if/else if on cumulative totals, or subtract tier by tier.

PF-E-021 · Short-Circuit Guard Drill

Difficulty: Intermediate · Lecture: L07 · Outcomes: PF-4.2 Prerequisites: E-020 Problem: Read a divisor and a dividend. Using one if with a short-circuit guard, print the quotient when the divisor is non-zero, otherwise print cannot divide. Then read a second pair and do the same without the guard — observe the crash (run it; note what happens in a comment). Input: two pairs of integers · Output: quotient or message. Sample: 0 5 → cannot divide / 2 9 → 4 Hints: (divisor != 0) && (...); the unguarded version is expected to misbehave — that's the lesson.

PF-E-022 · BMI Classifier

Difficulty: Intermediate · Lecture: L07 · Outcomes: PF-4.2, PF-3.2 Prerequisites: E-019 Problem: Read weight (kg) and height (m). Compute BMI = weight / height². Print the BMI (1 decimal) and the class: < 18.5 under, < 25 normal, < 30 over, else obese. Reject non-positive height/weight. Input: two doubles · Output: BMI and class word. Sample: 68 1.7 → 23.5 normal Hints: validate inputs first; the chain thresholds are the lower bounds of each class.

PF-E-023 · Simple Calculator (switch)

Difficulty: Intermediate · Lecture: L08 · Outcomes: PF-4.3 Prerequisites: E-021 Problem: Read two doubles and an operator character (+ - * /). Use a switch to print the result (2 decimals); division by zero prints undefined; any other operator prints unknown op. Input: double, char, double · Output: one value or message. Sample: 7 / 2 → 3.50 Hints: five cases + default; the zero-divisor test lives inside case '/'.

PF-E-024 · Days in Month (switch with fall-through groups)

Difficulty: Intermediate · Lecture: L08 · Outcomes: PF-4.3 Prerequisites: E-023 Problem: Read a month number (1–12) and a year. Print the number of days, using grouped case labels (31-day and 30-day groups) and a leap-year test for February. Reject months outside 1–12. Input: int, int · Output: one integer or invalid month. Sample: 2 2024 → 29 / 2 1900 → 28 Hints: reuse E-017's leap logic; grouped labels are the legitimate fall-through.

PF-E-025 · Rock-Paper-Scissors Arbitrator

Difficulty: Intermediate · Lecture: L08 · Outcomes: PF-4.3, PF-4.4 Prerequisites: E-024 Problem: Read two moves as characters (r, p, s) for players A and B. Print A wins, B wins, or draw. Validate moves first (invalid move). Implement the decision with a switch on player A nested inside validation — no chained if allowed. Input: two chars · Output: one phrase. Sample: r s → A wins / p p → draw Hints: only 3 non-draw pairs exist for A; enumerate them per case.

PF-E-026 · Tax Bracket Advisor (nested + guard clauses)

Difficulty: Advanced Introductory · Lecture: L08 · Outcomes: PF-4.2, PF-4.4 Prerequisites: E-022, E-026-level design Problem: Read annual taxable income (double, ≥ 0). Compute tax: 0% on the first 600,000; 5% of the next 400,000; 10% of the next 500,000; 15% beyond 1,500,000. Print tax owed and effective rate (2 decimals). Use guard clauses for invalid input (negative, non-numeric) and no nested ifs deeper than one level. Input: one double · Output: two money/percent values. Sample: 1200000 → tax: 50000.00 / effective: 4.17% Hints: compute per-band slices with early returns; the effective rate is tax/income × 100.