C++刷题学习记录一

#define _CRT_SECURE_NO_WARNINGS

#include<cstdio>
#include<vector>
#include <iostream>
#include<unordered_map>
using namespace std;
class Solution {
public:
	int findRepeatNumber(vector<int>& nums) {
		unordered_map<int, bool> map;
		for (int num : nums) {
			if (map[num]) return num;
			map[num] = true;
		}
		return -1;
	}
};
int main()
{	
	int out, outt;
	vector<int> vec{ 2, 3, 1, 0, 2, 5, 3 };
	for (int i = 0; i < 5; i++) {
		cout << vec[i] << endl;
	}
	vector<int>& vect = vec;
	cout << "============" << endl;
	 out = Solution().findRepeatNumber(vec);
	 cout << out << endl;
	 outt = Solution().findRepeatNumber(vect);
	 cout << outt << endl;
	 return 0;
}
#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
using namespace std;

// 函数声明
void swap(int& x, int& y);

int main()
{
	// 局部变量声明
	int a = 100;
	int b = 200;
	int& c = a;
	int& d = b;
	

	cout << "交换前,c 的值:" << c << endl;
	cout << "交换前,d 的值:" << d << endl;

	/* 调用函数来交换值 */
	swap(c, d);

	cout << "交换后,c 的值:" << c << endl;
	cout << "交换后,d 的值:" << d << endl;

	return 0;
}

// 函数定义
void swap(int& x, int& y)
{
	int temp;
	temp = x; /* 保存地址 x 的值 */
	x = y;    /* 把 y 赋值给 x */
	y = temp; /* 把 x 赋值给 y  */

	return;
}
#include <iostream>
using namespace std;
 
// 函数声明
void swap(int& x, int& y);
 
int main ()
{
   // 局部变量声明
   int a = 100;
   int b = 200;
 
   cout << "交换前,a 的值:" << a << endl;
   cout << "交换前,b 的值:" << b << endl;
 
   /* 调用函数来交换值 */
   swap(a, b);
 
   cout << "交换后,a 的值:" << a << endl;
   cout << "交换后,b 的值:" << b << endl;
 
   return 0;
}
 
// 函数定义
void swap(int& x, int& y)
{
   int temp;
   temp = x; /* 保存地址 x 的值 */
   x = y;    /* 把 y 赋值给 x */
   y = temp; /* 把 x 赋值给 y  */
  
   return;
}
#define _CRT_SECURE_NO_WARNINGS

#include<cstdio>
#include<vector>
#include <iostream>
#include<unordered_map>
using namespace std;
class Solution {
public:
	int findRepeatNumber(vector<int>& nums) {
		unordered_map<int, bool> map;
		for (int num : nums) {
			if (map[num] == true) return num;
			map[num] = true;
			for (auto iter = map.begin(); iter != map.end(); ++iter) {
				cout << "<" << iter->first << ", " << iter->second << ">" << endl;
			}
			cout << "+++++" << endl;
		}
		for (auto iter = map.begin(); iter != map.end(); ++iter) {
			cout << "<" << iter->first << ", " << iter->second << ">" << endl;
		}
		return -1;
	}
};
int main()
{
	int out, outt;
	vector<int> vec{ 2, 3, 1, 0, 2, 5, 3 };
	for (int i = 0; i < 7; i++) {
		cout << vec[i] << endl;
	}
	vector<int>& vect = vec;
	cout << "============" << endl;
	out = Solution().findRepeatNumber(vec);
	cout << out << endl;
	//outt = Solution().findRepeatNumber(vect);
	//cout << outt << endl;
	return 0;
}

具体来讲,unordered_map 容器和 map 容器一样,以键值对(pair类型)的形式存储数据,存储的各个键值对的键互不相同且不允许被修改。但由于 unordered_map 容器底层采用的是哈希表存储结构,该结构本身不具有对数据的排序功能,所以此容器内部不会自行对存储的键值对进行排序。
 

#define _CRT_SECURE_NO_WARNINGS

#include<cstdio>
#include<vector>
#include <iostream>
#include<unordered_map>
#include<map>
using namespace std;
class Solution {
public:
	int findRepeatNumber(vector<int>& nums) {
		map<int, bool> map;
		for (int num : nums) {
			if (map[num] == true) return num;
			map[num] = true;
			for (auto iter = map.begin(); iter != map.end(); ++iter) {
				cout << "<" << iter->first << ", " << iter->second << ">" << endl;
			}
			cout << "+++++" << endl;
		}
		for (auto iter = map.begin(); iter != map.end(); ++iter) {
			cout << "<" << iter->first << ", " << iter->second << ">" << endl;
		}
		return -1;
	}
};
int main()
{
	int out, outt;
	vector<int> vec{ 2, 3, 1, 0, 2, 5, 3 };
	for (int i = 0; i < 7; i++) {
		cout << vec[i] << endl;
	}
	vector<int>& vect = vec;
	cout << "============" << endl;
	out = Solution().findRepeatNumber(vec);
	cout << out << endl;
	//outt = Solution().findRepeatNumber(vect);
	//cout << outt << endl;
	return 0;
}
#define _CRT_SECURE_NO_WARNINGS

#include <cstdio>

// 参数:
//        numbers:     一个整数数组
//        length:      数组的长度
//        duplication: (输出) 数组中的一个重复的数字
// 返回值:             
//        true  - 输入有效,并且数组中存在重复的数字
//        false - 输入无效,或者数组中没有重复的数字
bool duplicate(int numbers[], int length, int* duplication)
{
	if (numbers == nullptr || length <= 0)
		return false;

	for (int i = 0; i < length; ++i)
	{
		if (numbers[i] < 0 || numbers[i] > length - 1)
			return false;
	}

	for (int i = 0; i < length; ++i)
	{
		while (numbers[i] != i)
		{
			if (numbers[i] == numbers[numbers[i]])
			{
				*duplication = numbers[i];
				return true;
			}

			// 交换numbers[i]和numbers[numbers[i]]             
			int temp = numbers[i];
			numbers[i] = numbers[temp];
			numbers[temp] = temp;
		}
	}

	return false;
}

// ====================测试代码====================
bool contains(int array[], int length, int number)
{
	for (int i = 0; i < length; ++i)
	{
		if (array[i] == number)
			return true;
	}

	return false;
}

void test(const char* testName, int numbers[], int lengthNumbers, int expected[], int expectedExpected, bool validArgument)
{
	printf("%s begins: ", testName);

	int duplication;
	bool validInput = duplicate(numbers, lengthNumbers, &duplication);

	if (validArgument == validInput)
	{
		if (validArgument)
		{
			if (contains(expected, expectedExpected, duplication))
				printf("Passed.\n");
			else
				printf("FAILED.\n");
		}
		else
			printf("Passed.\n");
	}
	else
		printf("FAILED.\n");
}

// 重复的数字是数组中最小的数字
void test1()
{
	int numbers[] = { 2, 1, 3, 1, 4 };
	int duplications[] = { 1 };
	test("Test1", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int), true);
}

// 重复的数字是数组中最大的数字
void test2()
{
	int numbers[] = { 2, 4, 3, 1, 4 };
	int duplications[] = { 4 };
	test("Test2", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int), true);
}

// 数组中存在多个重复的数字
void test3()
{
	int numbers[] = { 2, 4, 2, 1, 4 };
	int duplications[] = { 2, 4 };
	test("Test3", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int), true);
}

// 没有重复的数字
void test4()
{
	int numbers[] = { 2, 1, 3, 0, 4 };
	int duplications[] = { -1 }; // not in use in the test function
	test("Test4", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int), false);
}

// 没有重复的数字
void test5()
{
	int numbers[] = { 2, 1, 3, 5, 4 };
	int duplications[] = { -1 }; // not in use in the test function
	test("Test5", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int), false);
}

// 无效的输入
void test6()
{
	int* numbers = nullptr;
	int duplications[] = { -1 }; // not in use in the test function
	test("Test6", numbers, 0, duplications, sizeof(duplications) / sizeof(int), false);
}

int main()
{
	test1();
	test2();
	test3();
	test4();
	test5();
	test6();
	return 0;
}
#define _CRT_SECURE_NO_WARNINGS

#include <iostream>


int countRange(const int* numbers, int length, int start, int end);

// 参数:
//        numbers:     一个整数数组
//        length:      数组的长度
// 返回值:             
//        正数  - 输入有效,并且数组中存在重复的数字,返回值为重复的数字
//        负数  - 输入无效,或者数组中没有重复的数字
int getDuplication(const int* numbers, int length)
{
	if (numbers == nullptr || length <= 0)
		return -1;

	int start = 1;
	int end = length - 1;
	while (end >= start)
	{
		int middle = ((end - start) >> 1) + start;
		int count = countRange(numbers, length, start, middle);
		if (end == start)
		{
			if (count > 1)
				return start;
			else
				break;
		}

		if (count > (middle - start + 1))
			end = middle;
		else
			start = middle + 1;
	}
	return -1;
}

int countRange(const int* numbers, int length, int start, int end)
{
	if (numbers == nullptr)
		return 0;

	int count = 0;
	for (int i = 0; i < length; i++)
		if (numbers[i] >= start && numbers[i] <= end)
			++count;
	return count;
}

// ====================测试代码====================
void test(const char* testName, int* numbers, int length, int* duplications, int dupLength)
{
	int result = getDuplication(numbers, length);
	for (int i = 0; i < dupLength; ++i)
	{
		if (result == duplications[i])
		{
			std::cout << testName << " passed." << std::endl;
			return;
		}
	}
	std::cout << testName << " FAILED." << std::endl;
}

// 多个重复的数字
void test1()
{
	int numbers[] = { 2, 3, 5, 4, 3, 2, 6, 7 };
	int duplications[] = { 2, 3 };
	test("test1", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 一个重复的数字
void test2()
{
	int numbers[] = { 3, 2, 1, 4, 4, 5, 6, 7 };
	int duplications[] = { 4 };
	test("test2", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 重复的数字是数组中最小的数字
void test3()
{
	int numbers[] = { 1, 2, 3, 4, 5, 6, 7, 1, 8 };
	int duplications[] = { 1 };
	test("test3", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 重复的数字是数组中最大的数字
void test4()
{
	int numbers[] = { 1, 7, 3, 4, 5, 6, 8, 2, 8 };
	int duplications[] = { 8 };
	test("test4", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 数组中只有两个数字
void test5()
{
	int numbers[] = { 1, 1 };
	int duplications[] = { 1 };
	test("test5", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 重复的数字位于数组当中
void test6()
{
	int numbers[] = { 3, 2, 1, 3, 4, 5, 6, 7 };
	int duplications[] = { 3 };
	test("test6", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 多个重复的数字
void test7()
{
	int numbers[] = { 1, 2, 2, 6, 4, 5, 6 };
	int duplications[] = { 2, 6 };
	test("test7", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 一个数字重复三次
void test8()
{
	int numbers[] = { 1, 2, 2, 6, 4, 5, 2 };
	int duplications[] = { 2 };
	test("test8", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 没有重复的数字
void test9()
{
	int numbers[] = { 1, 2, 6, 4, 5, 3 };
	int duplications[] = { -1 };
	test("test9", numbers, sizeof(numbers) / sizeof(int), duplications, sizeof(duplications) / sizeof(int));
}

// 无效的输入
void test10()
{
	int* numbers = nullptr;
	int duplications[] = { -1 };
	test("test10", numbers, 0, duplications, sizeof(duplications) / sizeof(int));
}

void main()
{
	int i = 1, j = 7, out;
	out = j - i;
	std::cout << out << std:: endl;
	int middle = ((j - i) >> 1);//右移运算符
	std::cout << middle<< std::endl;
	test1();
	test2();
	test3();
	test4();
	test5();
	test6();
	test7();
	test8();
	test9();
	test10();
}

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