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Problem solving with variables, conditions, loops and functions, building up to small console programs.
Implement insertion, deletion and reversal on a singly linked list, and trace each pointer update.
Arrays, linked lists, stacks, queues, trees and graphs, with attention to the cost of each operation.
A short check on base cases and recursive calls, then one function to write from scratch.
Classes, encapsulation, inheritance and interfaces in Java and C#, through small domain models.
Timed and graded in lockdown mode: stacks, queues and command processing in C.
JavaScript and TypeScript from the language up: functions, collections, and parsing real input.
Open practice on recursive decomposition, traversal order and keeping track of state.
Print the indices of the two numbers that add up to the target.
n, target = map(int, input().split())nums = list(map(int, input().split())) seen = {}for i, x in enumerate(nums): if target - x in seen: print(seen[target - x], i) break seen[x] = ielse: print(-1)Process deposits and withdrawals, rejecting any that overdraw.
import java.util.Scanner; public class Main { static class Account { private long balance; void deposit(long amount) { balance += amount; } boolean withdraw(long amount) { if (amount > balance) return false; balance -= amount; return true; } } public static void main(String[] args) { Scanner in = new Scanner(System.in); Account account = new Account(); int q = in.nextInt(); while (q-- > 0) { String op = in.next(); long amount = in.nextLong(); if (op.equals("deposit")) { account.deposit(amount); } else if (!account.withdraw(amount)) { System.out.println("Insufficient funds"); } } System.out.println(account.balance); }}Reason about running time before writing any code.
What is the time complexity of binary search on a sorted array?
O(1)O(log n)Correct answerO(n)O(n log n)Which of these run in linear time?
Select all that apply.
An O(n²) algorithm is always slower than an O(n) one.
Doubling n roughly Blank 1 the running time of an O(n²) algorithm.
Print a matrix's values in clockwise spiral order.
#include <stdio.h> int printed = 0; void out(int value) { printf(printed++ ? " %d" : "%d", value);} int main(void) { int r, c, m[20][20]; scanf("%d %d", &r, &c); for (int i = 0; i < r; i++) for (int j = 0; j < c; j++) scanf("%d", &m[i][j]); int top = 0, bottom = r - 1; int left = 0, right = c - 1; while (top <= bottom && left <= right) { for (int j = left; j <= right; j++) out(m[top][j]); top++; for (int i = top; i <= bottom; i++) out(m[i][right]); right--; if (top <= bottom) { for (int j = right; j >= left; j--) out(m[bottom][j]); bottom--; } if (left <= right) { for (int i = bottom; i >= top; i--) out(m[i][left]); left++; } } printf("\n"); return 0;}For each line, print YES if every bracket is closed in order.
const fs = require("fs");const lines = fs.readFileSync(0, "utf8").trim().split("\n");const pairs = { ")": "(", "]": "[", "}": "{" }; for (const line of lines.slice(1)) { const stack = []; let ok = true; for (const ch of line.trim()) { if ("([{".includes(ch)) { stack.push(ch); } else if (ch in pairs && stack.pop() !== pairs[ch]) { ok = false; break; } } console.log(ok && stack.length === 0 ? "YES" : "NO");}Inheritance, access and abstraction, checked before the lab.
Which keyword lets a class reuse another class's fields and methods?
Which access modifier makes a member visible only inside its own class?
publicprotectedprivateCorrect answerA Java class can extend more than one class.
Explain the difference between an abstract class and an interface, with an example of when you would use each.
Up to 150 words.
2 pts: a correct distinction. 2 pts: a fitting example for each. 1 pt: clear writing.
Average each student's scores and assign a letter grade.
using System;using System.Linq; class Program{ static string Letter(double average) { if (average >= 90) return "A"; if (average >= 80) return "B"; if (average >= 70) return "C"; return "F"; } static void Main() { int n = int.Parse(Console.ReadLine()); for (int i = 0; i < n; i++) { string[] parts = Console.ReadLine().Split(' '); double average = parts.Skip(1) .Select(s => double.Parse(s)) .Average(); Console.WriteLine( $"{parts[0]} {average:F1} {Letter(average)}"); } }}Answer each query with the index of the value, or -1.
declare const require: (id: "fs") => { readFileSync(fd: number, encoding: "utf8"): string;}; const input: string[] = require("fs") .readFileSync(0, "utf8") .trim() .split("\n");const nums: number[] = input[1].split(" ").map(Number); function binarySearch(arr: number[], target: number): number { let lo = 0; let hi = arr.length - 1; while (lo <= hi) { const mid = (lo + hi) >> 1; if (arr[mid] === target) return mid; if (arr[mid] < target) lo = mid + 1; else hi = mid - 1; } return -1;} for (const q of input[2].split(" ").map(Number)) { console.log(binarySearch(nums, q));}Addresses, dereferencing, and what makes behavior undefined.
Given int x = 5; int *p = &x;, what does *p evaluate to?
5Correct answerxpThe Blank 1 operator gives the address of a variable, and the Blank 2 operator dereferences a pointer.
Which of these cause undefined behavior?
Select all that apply.
NULLCorrect answerfreeCorrect answerCalling free twice on the same pointer is safe.
Print the three most frequent words, ties broken alphabetically.
import sysfrom collections import Counter words = sys.stdin.read().lower().split()counts = Counter(w.strip(".,!?") for w in words)ranked = sorted(counts.items(), key=lambda p: (-p[1], p[0])) for word, count in ranked[:3]: print(f"{word} {count}")Read n values into a linked list and print it reversed.
#include <stdio.h>#include <stdlib.h> typedef struct Node { int value; struct Node *next;} Node; Node *push(Node *head, int value) { Node *node = malloc(sizeof(Node)); node->value = value; node->next = head; return node;} int main(void) { int n, x; Node *head = NULL; scanf("%d", &n); for (int i = 0; i < n; i++) { scanf("%d", &x); head = push(head, x); } for (Node *p = head; p; p = p->next) printf(p->next ? "%d " : "%d\n", p->value); return 0;}A short write-up after the week's lab, plus two checks.
Describe a bug you hit this week: how you located it, and what you changed to fix it.
Up to 200 words.
2 pts: a specific bug. 2 pts: a clear debugging process. 1 pt: what the fix was and why it works.
What do we call a test that uses the smallest or largest valid input?
A program that passes every visible test case is guaranteed to pass the hidden ones.
Answer a few questions, or describe the whole exercise in one sentence. AI drafts the title, summary, statement and tags.
AI writes a reference solution and the files students start from. Lock a file so students can read it but not edit it, or hide it entirely.
AI suggests test cases aimed at common student mistakes. One click fills in every expected output by running your solution.
Require or forbid keywords, like banning qsort so students write their own sort. A violation scores the item 0 by default, and you can change the penalty.
Ask for changes in your own words. AI edits the problem statement, and you apply it when it reads right.
Before students see it, AI reviews the statement, solution, starter code and test cases together, and flags what is missing.
Every teacher's exercises in one bank, in Java, Python, C and more. Browse by author, or keep to your own.
Schedule it, set time limits, access codes and lockdown, choose who takes it and when answers show.
Write the page students land on, with files and links that turn into cards.
Invite students, share a join code, or require approval, and watch the roster fill up.
Sort students into color-coded groups, like a class section or an extra-practice group.
Hidden test cases score each submission, and AI rates its hard-coding risk and code quality.
A gradebook for every course, with class stats at a glance, color-banded scores and filters by group.
