Yaolong Huang airekans

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airekans.github.io

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airekans / string_reverse.cpp

Created August 6, 2013 15:50

[OJ] Careerup Top 150(1.2): Write code to reverse a C-Style String. (C-String means that “abcd” is represented as five characters, including the null character.)

	void reverse(const char* s, char* res)
	{
	int count = 0;
	reverse_impl(s, res, count);
	res[count] = '\0';
	}

	void reverse_impl(const char* s, char* res, int& count)
	{
	if (s[0] != '\0')

airekans / remove_duplicate.cpp

Created August 6, 2013 16:17

[OJ] Careercup Top 150(1.3): Solution: 1. O(n^2): loop directly to remove duplicate, then compact. 2. O(lg n): sort then remove duplicate, then compact.

	// O(n^2) solution
	void remove_duplicate(char* s)
	{
	const int size = strlen(s);
	for (int i = 0; i < size - 1; ++i)
	{
	if (s[i] == '\0')
	{
	continue;
	}

airekans / bit_convert.cpp

Last active December 20, 2015 18:59

[OJ] Careercup Top 150(5.5): Solution: Write a function to count the number of 1 in a number, then we use XOR to get the number of different bits between A and B.

	// A rather simple but elegant solution.
	int get_bit_num(unsigned int num)
	{
	int count = 0;
	while (num != 0)
	{
	num &= num - 1;
	++count;
	}
	return count;

airekans / nth_last.cpp

Created August 9, 2013 11:47

[OJ] Careercup Top 150(2.2). I define the nth to last element to be the the node needs to move n steps to get to the last element. So if I want to find the second to last element of a 3-node list, it would be the first node.

	struct Node
	{
	int data;
	Node* next;
	};

	Node* nth_last(Node* list, const int n)
	{
	Node* nth = list;
	int count = 0;

airekans / queue_in_stacks.cpp

Created August 9, 2013 11:55

[OJ] Careercup Top 150(3.5):

	#include <stack>

	class MyQueue
	{
	std::stack<int> m_first;
	std::stack<int> m_second;
	public:
	void Push(int value)
	{
	m_first.push(value);

airekans / is_tree_balanced.cpp

Last active December 20, 2015 20:49

[OJ] Careercup Top 150(4.1): balance tree checking

	struct Node
	{
	int data;
	Node* left;
	Node* right;
	};

	bool is_balanced(const Node* node)
	{
	int depth = 0;

airekans / next_in_order.cpp

Last active December 20, 2015 20:49

[OJ] Careercup Top 150(4.5): next in order

	struct Node
	{
	int data;
	Node* left;
	Node* right;
	Node* parent;
	};

	Node* next_in_order(const Node* node)
	{

airekans / prime_circular.cpp

Created August 10, 2013 02:34

[OJ] 素数环: 输入一个整数n, 将整数1, 2, 3, ..., n弄成一个环，使得相邻的两个数的和是素数。输出所有的环，从1开始逆时针的输出。 Solution: 回溯，然后剪枝。

	// prime circular list

	const int MAXN = 100;
	static int primes[MAXN];

	void gen_primes(const int n)
	{
	for (int i = 1; i * i <= n; ++i)
	{
	for (int j = 1; i * j <= n; ++j)

airekans / find_union_set.cpp

Created August 11, 2013 13:48

Union Find Set(并查集): 基本操作(优势)：1. 查找某个元素所在的集合; 2. 合并两个不相交的集合。目前看到比较多的实现都是基于数组的。

	// Union Find Set

	const int MAXN = 100;
	int father[MAXN] = {0};
	int rank[MAXN] = {0};

	int find_set(const int x)
	{
	if (father[x] != x)
	{

airekans / trie.cpp

Created August 13, 2013 06:41

Trie implementation

	sturct TrieNode
	{
	TrieNode()
	{
	memset(next, 0, 26 * sizeof(TrieNode*));
	count = 0;
	}

	TrieNode* next[26]; // We assume that only alphabetical char will be present.
	int count;

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