[C language practice - adjust the order of odd and even numbers in the array]

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Preface

Adjust the order of odd and even numbers in the array , Make all odd numbers precede even numbers .

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1、 Do not change element order

• First, adjust the odd numbers to the front of the array
• Then adjust the even numbers to the end of the array
• The sequence of all odd parts remains the same
• The sequence of all even parts remains the same

int main()
{
    
	int a[] = {
     1,2,8,9,4,10,3,5,6,0,7 };
	int left = 0;
	int sz = sizeof(a) / sizeof(a[0]);
	int right = sz-1;
	int tmp = 0;// Temporary intermediate variable 
	int num = sz;// Judge the number of times 
	while (num)
	{
    
		if (a[left] % 2 == 0)// here a[left] It's even , Shift 
		{
    
			//ou = i;// The starting position of the next judgment 
			tmp = a[left];
			for (int j = left; j <= right - 1; j++)
			{
    
				a[j] = a[j + 1];
			}
			a[right] = tmp; // Even numbers at the end of the array 
		}
		else
		{
    
			left++;//a[left] Not even numbers , Then judge the next a[left+1]
		}
		num--;
	}
	for (int  i = 0; i < sz; i++)
	{
    
		printf("%d ", a[i]);
	}
	return 0;
}

The results are as follows ：

10

2、 Change the order of elements

• First, adjust the odd numbers to the front of the array
• Then adjust the even numbers to the end of the array
• The sequence of all odd parts is changed
• The sequence of all even parts has changed

void change(int a[], int sz)
{
    
	int left = 0;
	int right = sz - 1;
	while (left<right)
	{
    
		while ((left<right) && (a[left] % 2 == 1))
		{
    
			left++;
		}
		while ((left < right) && (a[right] % 2 == 0))
		{
    
			right--;
		}
		if (left < right)
		{
    
			int tmp = a[left];
			a[left] = a[right];
			a[right] = tmp;
		}
	}
}
void print(int a[], int sz)
{
    
	int i = 0;
	for (i = 0; i < sz; i++)
	{
    
		printf("%d ", a[i]);
	}
}
int main()
{
    
	int a[] = {
     1,2,8,9,4,10,3,5,6,0,7 };
	int sz = sizeof(a) / sizeof(a[0]);
	change(a, sz);
	print(a, sz);
	return 0;
}

The results are as follows ：

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summary

Still need more practice , No matter the code you write is wordy , Still too bad , You have to finish it , Achieve the requirements of the topic , This is the most important step .

The second step is to look at the code written by others , Learn other people's ideas , Write it down and blog , Convenient for self review .