C的数据结构练习2---数组

1.单调数列

//单调数列
#include 
#include 
#include 
#include 

//递增
bool Inc_Seq(int *arr, int num)
{
	bool res = true;
	for (int i = 0; i < num-1; i++)
	{
		if (arr[i]>arr[i + 1])
		{
			res = false;
			break;
		}
	}
	return res;
}

//递减
bool Dec_Seq(int *arr, int num)
{
	bool res = true;
	for (int i = 0; i < num - 1; i++)
	{
		if (arr[i] < arr[i + 1])
		{
			res = false;
			break;
		}
	}
	return res;
}


bool Is_Monoton(int *arr, int num)
{
	assert(arr != NULL);
	return Inc_Seq(arr, num) || Dec_Seq(arr, num);
}


int main()
{
	int arr[] = { 12, 23, 34, 45, 56, 67, 78, 89, 90, 100 };
	int brr[] = { 100, 90, 89, 78, 67, 56, 45, 34, 23, 12 };
	int crr[] = { 89, 78, 65, 23, 12, 58, 64, 67, 45 };
	int size = sizeof(arr) / sizeof(arr[0]);
	printf("%d n", Is_Monoton(arr, size));
	size = sizeof(brr) / sizeof(brr[0]);
	printf("%d n", Is_Monoton(brr, size));
	size = sizeof(crr) / sizeof(crr[0]);
	printf("%d n", Is_Monoton(crr, size));
	system("pause");
	return 0;
}

2.数组中寻找重复的数

暴力破解法：

#include 
#include 
#include 

int Find_Duplicate_Arr(int *arr, int size)
{
	assert(arr != NULL);
	int tmp = 0;
	for (int i = 0; i < size; i++)
	{
		tmp = arr[i];
		for (int j = i + 1; j < size; j++)
		{
			if (tmp == arr[j])
			{
				goto end;
			}
		}
	}
	end:
	return tmp;
}

int main()
{
	int arr[] = { 1, 2, 3, 4, 5, 6, 2, 2 };
	int size = sizeof(arr) / sizeof(arr[0]);
	printf("%d n", Find_Duplicate_Arr(arr, size));
	system("pause");
	return 0;
}

3.将数组有序后，寻找重复元素

#include 
#include 
#include 

int Compar_ints(const void *a, const void *b)
{
	int arg1 = *(const int *)a;
	int arg2 = *(const int *)b;
	if (arg1 < arg2)
	{
		return 1;
	}
	else if(arg1>arg2)
	{
		return -1;
	}
	else
	{
		return 0;
	}
}

int Find_Duplicate_Sort_Arr(int *arr, int size)
{
	assert(arr != NULL);
	qsort(arr, size, sizeof(int), Compar_ints);
	int tmp = 0;
	for (int i = 0; i < size - 1; i++)
	{
		if (arr[i] == arr[i + 1])
		{
			tmp = arr[i];
			break;
		}
	}
	return tmp;
}

int main()
{

	int arr[] = { 1, 2, 3, 4, 5, 6, 3, 7 };
	int size = sizeof(arr) / sizeof(arr[0]);
	printf("%d n", Find_Duplicate_Sort_Arr(arr, size));
	system("pause");
	return 0;
}

4.查表法---以空间换时间

#include 
#include 
#include 
int Find_Duplicate_Table_Method_Arr(int *arr, int count)
{
	assert(arr != NULL);
	int*newdata = (int *)calloc(count,sizeof(int));
	if (newdata == NULL)
	{
		return -1;
	}
	int idx = 0;
	for (int i = 0; i < count; i++)
	{
		if (newdata[arr[i]] == 0)
		{
			newdata[arr[i]] = 1;
		}
		else
		{
			idx = arr[i];
			break;
		}
	}
	free(newdata);
	newdata = NULL;
	return idx;
}

int main()
{
	int arr[] = { 1, 2, 3, 4, 5, 4 };
	const int count = sizeof(arr) / sizeof(arr[0]);
	printf("%d n", Find_Duplicate_Table_Method_Arr(arr, count));
	system("pause");
	return 0;
}