SSowmiyainsowmiya.hashnode.dev·May 7 · 4 min readSolving DSA Series - A word on HashMap and Two PointersHello readers! Welcome to my Solving DSA Problems Series - Part 1 In this piece, we're going to be looking at two of the basic concepts - HashMap and Two Pointers. If these terms doesn't feel familiar00
SKShubham Kumar Singhinblog.realdev.club·Apr 7 · 3 min readSegregate 0s and 1s (In-Place Sorting)When I first saw this problem, it looked very simple… But it actually teaches an important concept:How to optimize from 2 passes → 1 pass using two pointers Problem Statement You are given an array c00
MSMuppidi Srinivasinsrinivastechblog.hashnode.dev·Mar 16 · 4 min readSliding Window Technique: A Powerful Tool for Subarray ProblemsSliding Window Technique When solving array or string problems in competitive programming, we often deal with subarrays or substrings. A naive solution usually checks every possible subarray, which le00
ACA Curious Coderinclarity-in-code.hashnode.dev·Feb 14 · 3 min readTwo PointersWhy Do We Even Need Two Pointers? When we first learn arrays, our brain naturally jumps to nested loops. Want to find a pair?Use two loops. Want to compare elements?Two loops. Works? Yes.Efficient? Not really. If an array has 10,000 elements, O(n²) m...00
DKDeepak Kambalaintwo-sum-2.hashnode.dev·Feb 13 · 1 min read167. Two Sum II - Input Array Is Sortedhttps://leetcode.com/problems/two-sum-ii-input-array-is-sorted/description/ Array is sorted Return 1-based indices Exactly one solution guaranteed Core Idea (Two Pointer Technique) Use two pointers: left → start of array right → end of array ...00
TTanishiincodingchallenge.hashnode.dev·Jan 8 · 2 min readDay 9 – Intersection of Two Linked Lists | Two Pointer | LeetCode Challenge🗓️ Date: January 9, 2026📌 Challenge:🧩 Problem: Intersection of Two Linked Lists – LeetCode #160 (Easy)💻 Topic: Two Pointer, Linked List ✅ Problem Statement (Summary): Goal: Given the heads of two singly linked lists headA and headB, return the n...00
GGauravinigaurav.hashnode.dev·Dec 22, 2025 · 8 min readWhat Makes the Two-Pointer Technique So EffectiveI remember the first time I encountered the two-pointer technique in my Data Structures class. My professor threw this problem at us: "Find two numbers in a sorted array that add up to a target." My immediate thought? "Easy! Just use two loops and ch...00
SAShahwar Alam Naqviinis-power-of-two.hashnode.dev·Dec 16, 2025 · 2 min readLeetCode: Check If String Is a Prefix of ArrayProblem: https://leetcode.com/problems/check-if-string-is-a-prefix-of-array/description/ Code: class Solution: def isPrefixString(self, s: str, words: List[str]) -> bool: index=0 for word in words: if not s.startswith(...00
NNikhithainbugfreenik.hashnode.dev·Nov 25, 2025 · 2 min readBoats to Save PeopleHey Coders, Today we are going to understand and solve the Boats to Save People problem from LeetCode. Problem: we are given an array consisting of people’s weights , limit (capacity of a boat)and asked to find the minimum number of boats required. C...00
SAShahwar Alam Naqviinis-power-of-two.hashnode.dev·Nov 25, 2025 · 1 min readLeetCode: Boats to Save PeopleProblem: https://leetcode.com/problems/boats-to-save-people/description/ Code: class Solution: def numRescueBoats(self, people: List[int], limit: int) -> int: people.sort() boats=0 left, right = 0, len(people)-1 w...00
