Syntax for coding interviews

Code snippets for tech interviews

Not LeetCode. The syntax fundamentals you need — iterating lists, using hash maps, processing strings — compared across Python, JS, Java, Go and C++.

Iterating an array — 6 languages, all runnableRun it live

Python

arr = [1, 2, 3]

for x in arr:
    print(x)

# With index
for i, x in enumerate(arr):
    print(i, x)

Java

int[] arr = {1, 2, 3};

for (int x : arr) {
    System.out.println(x);
}

// With index
for (int i = 0; i < arr.length; i++) {
    System.out.println(i + " " + arr[i]);
}

Go

arr := []int{1, 2, 3}

for _, x := range arr {
    fmt.Println(x)
}

// With index
for i, x := range arr {
    fmt.Println(i, x)
}

22 snippets · 6 languages · 46 variantsOpen full snippet with editor →

Topics

Iteration3 snippets

Iterating Arraysfor, while, for-each — and how to get the index

Iterating StringsWalking a string character by character

Iterating Hash MapsLoop over keys, values, or both at the same time

Lists & Arrays1 snippets

List FundamentalsAdd, remove, access — the everyday bread-and-butter operations

Hash Maps1 snippets

Hash Map BasicsCreate, read, write, check — the 4 core operations

SetsDeduplication, membership checks, set operations

Strings3 snippets

String OperationsSplit, join, replace, search, convert

String BuilderBuild strings efficiently in a loop — never use + inside loops

Character OperationsChar ↔ int, isDigit, isLetter, alphabet index — used constantly in interviews

Functional1 snippets

Functional Programmingmap, filter, reduce — and what lambda syntax looks like in each language

Sorting1 snippets

SortingDefault sort, custom comparator, sort by key

Integer Tricks2 snippets

Integer TricksDigit extraction, reversal, digit sum — via modulo, not string conversion

Math Functionsabs, min, max, pow, sqrt — and overflow-safe integer limits

Type Conversion1 snippets

Types & ConversionInt↔String, String↔List, type casting

Patterns8 snippets

Two PointersOpposite ends shrinking inward, or fast/slow on the same array

Binary SearchThe template that avoids off-by-one bugs — and why mid = lo + (hi-lo)//2

Sliding WindowExpand right freely, shrink left when the window becomes invalid

Priority Queue / HeapGet the min or max in O(log n) — and how max-heap differs per language

Deque (Double-Ended Queue)Push/pop from both ends in O(1) — the backbone of BFS and sliding window max

Bit Tricksn & 1, n & (n-1), XOR patterns — O(1) operations that replace loops

StackLIFO — push, pop, peek. Used for brackets, undo, monotonic patterns

Prefix SumSubarray sum in O(1) after O(n) setup — the trick behind most subarray problems