Counting Bits In a Number – Leetcode

Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1‘s in the binary representation of i. Example 1: Input: n = 2 Output: [0,1,1] Explanation: 0 –> 0 1 –> 1 2 –> 10 Example 2: Input: n = 5 Output: [0,1,1,2,1,2] Explanation: 0 –> 0 1 –> 1 2…

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Time Needed to Inform All Employees – Leetcode [TREE, DFS]

A company has n employees with a unique ID for each employee from 0 to n – 1. The head of the company is the one with headID. Each employee has one direct manager given in the manager array where manager[i] is the direct manager of the i-th employee, manager[headID] = -1. Also, it is guaranteed that the subordination relationships have a tree structure. The head of the…

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String to Integer (atoi)

Implement atoi which converts a string to an integer. The function first discards as many whitespace characters as necessary until the first non-whitespace character is found. Then, starting from this character, takes an optional initial plus or minus sign followed by as many numerical digits as possible, and interprets them as a numerical value. The string can contain…

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