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Articles tagged with #dsa
1. Subset Sum (Leetcode 78: Subsets) Problem: Return all possible subsets (the power set) of a given array of distinct integers. Intuition: At each index, we have two choices: include or exclude the current element. void solve(int i, vector<int>& num...
1. N Meetings in One Room Problem: Given start[] and end[] times of meetings, find the maximum number of meetings that can be held in one room where only one meeting can happen at a time. Intuition: Sort meetings by end time. Always pick the meeting ...
Leetcode 237. Delete Node in a Linked List Intuition: You’re given access to the node itself, not the head. Copy data from next node, then delete the next node. void deleteNode(ListNode* node) { node->val = node->next->val; node->next = node-...
Insert Node at Head Intuition: Create a new node, point it to the current head, and update the head. Node* insertAtHead(Node* head, int val) { Node* newNode = new Node(val); newNode->next = head; return newNode; } // TC: O(1) // SC: O(1) ...
Leetcode 62 – Unique Paths Problem: From top-left of an m x n grid, reach the bottom-right using only right/down moves. 1. Brute Force (Recursion) Intuition: Try all paths recursively. int count(int i, int j, int m, int n) { if (i >= m || j >= n...
Count Inversions (Merge Sort Based) Counts pairs (i, j) such that i < j and arr[i] > arr[j]. int merge(vector<int>& arr, int low, int mid, int high) { vector<int> temp; int i = low, j = mid + 1, cnt = 0; while (i <= mid && j <= high) { ...