Here are some of my programming practices
TwoNumbers:
Given some integers (negative ones are permitted) which are placed in a vector.
Then a target number is given. We should find two numbers that the sum of them is equal to the target
among the input. The answer should be the places of them in the vector and we assume that there's only
a pair of them could result in the answer. Ex: [1, 2, 3, 4], 6 => index[1, 3]
ReverseInteger:
Given a 32-bit integer, then print the reverse of it. If overflow, print 0 instead.
BinartCarryBits:
Given a decimal number N, find the number of carry bits needed when N+1 in binary format.
ex:
N = 1 => N = 01, N+1 = 10 => #carry bits = 1
N = 7 => N = 0111, N+1 = 1000 => #carry bits = 3
N = 4 => N = 100, N+1 = 101 => #carrt bits = 0
SumOfPerfectSquare:
Given a, b. Find the sum of all perfect square numbers between a and b.
ex: (a, b) = (1, 10) => sum = 1 + 4 + 9 = 14
SpaceDivision:
Determine that how much different space could be divided by n non-parallel and different planes.
LongestCommonPrefix:
ex: ["abcde", "abced", "adcbe"] => lcp = "a"; ["abcde", "fghij"] => lcp = ""
RemoveDuplicates:
Given a sorted vector of integers, print it without duplicate integers.
RemoveElement:
Given a vector of integers and a target value, print the elements of the vector without target value.
CountAndSay:
Given a target value n, output a specific string.
The rule is below:
n = 1 => "1"
n = 2 => "11", which is one "1"
n = 3 => "21", which is two "1"
n = 4 => "1211", which is one "2", one "1"
n = 5 => "111221", which is one "1", one "2", two "1"
We count each number occurs in the n-th string, output(say) as the (n+1)-th string.
ClimbStairs:
Given an integer which is the number of steps. We can take one or two steps each time.
Find how many different ways of climbing stairs there are.
ex: 1 => (1); 2 => (1, 1), (2); 3 => (1, 1, 1), (1, 2), (2, 1)
LongestSubstringWithoutDuplicates:
Given a string, find the first longest substring which isn't made of repeating characters.
Output its length.
ex: abcabcbb => abc(3); pwwke => wke(3); abcdebasjga => cdebasjg(8)
LongestValidParenthese:
Given a string only made of '(' and ')', find the length of longest valid parenthese substring
ex: (()) => 4; (()()(() => 4; ((())) => 6
The key to this is to put the indices of the brackets in a stack. If there's a match then pop out
In the end, the longest length will be the length of whole string if the stack is empty because
all brackets are matched. Otherwise, the elements of stack point out the indices of the brackets
which cannot be matched, which means the substrings between these brackets are the valid parenthese.
Thus, It is just comparing each length of valid substrings that we can find the longest one.
FactorialTrailingZeroes:
Given a integer n, count the number of trailing zeroes in n!
ex: 3! = 6, #0 = 0; 5! = 120, #0 = 1; 7! = 5040, #0 = 1