706. Design HashMap

Problem description:

Design a HashMap without using any built-in hash table libraries.

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218. The Skyline Problem

Problem description:

A city’s skyline is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. Given the locations and heights of all the buildings, return the skyline formed by these buildings collectively.

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1248. Count Number of Nice Subarrays

Problem description:

Given an array of integers nums and an integer k. A continuous subarray is called nice if there are k odd numbers on it.

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1312. Minimum Insertion Steps to Make a String Palindrome

Problem description:

Given a string s. In one step you can insert any character at any index of the string.

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310. Minimum Height Trees

Problem description:

A tree is an undirected graph in which any two vertices are connected by exactly one path. In other words, any connected graph without simple cycles is a tree.

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261. Graph Valid Tree

Problem description:

You have a graph of n nodes labeled from 0 to n - 1. You are given an integer n and a list of edges where edges[i] = [ai, bi] indicates that there is an undirected edge between nodes ai and bi in the graph.

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1804. Implement Trie II (Prefix Tree)

Problem description:

A trie (pronounced as “try”) or prefix tree is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.

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1871. Jump Game VII

Problem description:

You are given a 0-indexed binary string s and two integers minJump and maxJump. In the beginning, you are standing at index 0, which is equal to '0'. You can move from index i to index j if the following conditions are fulfilled:

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398. Random Pick Index

Problem description:

Given an integer array nums with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array.

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528. Random Pick with Weight

Problem description:

You are given an array of positive integers w where w[i] describes the weight of ith index (0-indexed).

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