C语言零移位操作

给定一个整形数组要求把其中的零元素移动到数组的末尾非零元顺序保持不变

以下采用两种方法实现

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <windows.h>

void PrintArr( int arr[], int iSize )
{
	if( iSize < 0 )
		return;
	
	int i = 0;
	for( ; i < iSize; i++ )
	{
		if( !arr[i] )
			printf( "%d ", arr[i] );
	}

	puts( "" );
}

void LocalMove( int arr[], int iSize )
{//本地移动 速度极慢 优点是消耗内存空间少
	if( iSize <= 1 )
		return;

	int i,j;

	int iZeroCount = 0;//零元总数

	for( i = 0; i < iSize; i++ )
	{
		if( !arr[i] )
			iZeroCount++;
	}

	int iZeroCur = iZeroCount;
	
	for( i  = 0; i < iSize && iZeroCur > 0; i++ )
	{
		if( !arr[i] )
		{
			for( j = i; j < iSize - ( iZeroCount - iZeroCur ); j++ )
			{
				arr[j] = arr[j+1];
			}

			arr[j-1] = 0;
			iZeroCur--;
			i--;
		}
	}

	//PrintArr( arr, iSize );
}

int* CreateIntArr( int iSize )
{//创建整形数组
	puts( "CreateArr" );

	int* pIntArr = (int*)malloc( sizeof( int ) * iSize );

	if( !pIntArr )
		return NULL;

	srand( iSize );

	int i = 0;
	for( ; i < iSize; i++ )
	{
		if( 0 == i % 2 )
			*( pIntArr + i ) = rand();
		else
			*( pIntArr + i ) = 0;
	}

	puts( "Finish create array!" );

	return pIntArr;	
}

int* CopyArr( int* pArrInt, int iSize )
{//复制整形数组
	if( !pArrInt || iSize <= 0 )
		return  NULL;

	int* pNewArr = (int*)malloc( sizeof( int ) * iSize );

	if( !pNewArr )
		return NULL;

	puts( "Starting copy array ..." );
	int i = 0;
	for( ; i < iSize; i++ )
	{
		*( pNewArr + i ) = *( pArrInt + i );
	}

	puts( "Finish copy array..." );

	return pNewArr;
}
void SaveMove( int arr[], int iSize )
{//空间换时间 这个算法的速度是上个算法速度的8万倍以上 这个专卖值得做
	if( iSize <= 1 )
		return;

	int i  = 0;
	int iNoneZero = 0;

	for( ; i < iSize; i++ )
	{
		if( arr[i] )
			iNoneZero++;
	}

	int* pIntArr = (int*)malloc( sizeof( int ) * iNoneZero );
	int iCur = 0;
	for( i = 0; i < iSize && iNoneZero > 0; i++ )
	{
		if( arr[i] )
		{
			*(pIntArr + iCur++) = arr[i];
			iNoneZero--;
		}
	}
	
	memset( arr, 0, iSize );
	for( i = 0; i < iCur; i++ )
	{
		arr[i] = *( pIntArr + i );
	}

	//PrintArr( arr, iSize );
}



int main( int argc, char* argv[] )
{
	if( argc < 2 )
	{
		puts( "Usage: MoveZero.exe number" );
		return -1;
	}

	int iNum = atoi( argv[1] );

	if( iNum <= 0 )
	{
		puts( "Error argument!" );
	}

	int* pIntArrOne = CreateIntArr( iNum );
	int* pIntArrTwo = CopyArr( pIntArrOne, iNum );

	long lStart;
	
	lStart = GetTickCount();
	puts( "LocalMove" );
	LocalMove( pIntArrOne, iNum );
	printf( "LocalMove Cost Time: %ld\n", GetTickCount() - lStart );

	lStart = GetTickCount();
	puts( "SaveMove" );
	SaveMove( pIntArrTwo, iNum );
	printf( "SaveMove Cost Time: %ld\n", GetTickCount() - lStart );

	return 0;
}

测试结果如下：

C:\Users\fzql>"F:\MyDocument\Visual Studio 2008\Projects\VCInterview\VCInterview
\Debug\VCInterview.exe" 102400
CreateArr
Finish create array!
Starting copy array ...
Finish copy array...
LocalMove
LocalMove Cost Time: 16208
SaveMove
SaveMove Cost Time: 0

C:\Users\fzql>"F:\MyDocument\Visual Studio 2008\Projects\VCInterview\VCInterview
\Debug\VCInterview.exe" 1024000
CreateArr
Finish create array!
Starting copy array ...
Finish copy array...
LocalMove
LocalMove Cost Time: 1377832
SaveMove
SaveMove Cost Time: 16

C语言零移位操作

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