Question

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

Question

Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once.

For example:

Given nums = [1, 2, 1, 3, 2, 5], return [3, 5].

Question

Given an array of integers, every element appears three times except for one, which appears exactly once. Find that single one.

Question

Given an array of integers, every element appears twice except for one. Find that single one.

Question

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

Question

Implement regular expression matching with support for ‘.’ and ‘*’.

 '.' Matches any single character.
 '*' Matches zero or more of the preceding element.

 The matching should cover the entire input string (not partial).

 The function prototype should be:
 bool isMatch(const char *s, const char *p)

 Some examples:
 isMatch("aa","a") → false
 isMatch("aa","aa") → true
 isMatch("aaa","aa") → false
 isMatch("aa", "a*") → true
 isMatch("aa", ".*") → true
 isMatch("ab", ".*") → true
 isMatch("aab", "c*a*b") → true

Question

Validate if a given string is numeric. You may assume that each input would have exactly one solution.

Some examples:

"0" => true
" 0.1 " => true
"abc" => false
"1 a" => false
"2e10" => true

Question

Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would have exactly one solution.

Example:

Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

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