ex);
}
free(pFlag);
return;
}
void get_lost_number(int data[], int length)
{
int index;
RANGE range[4] = {0};
assert(NULL != data && 0 != length);
unsigned char* pFlag = (unsigned char*)malloc((length + 7) >> 3);
memset(pFlag, 0, length * sizeof(unsigned char));
range[0].start = 0, range[0].end = length >> 2;
range[1].start = length >> 2 , range[1].end = length >> 1;
range[2].start = length >> 1 , range[2].end = length >> 2 * 3;
range[3].start = length >> 2 * 3, range[3].end = length;
#pragma omp parallel for
for(index = 0; index < 4; index ++){
_get_lost_number(data, range[index].start, range[index].end, pFlag);
}
for(index = 0; index < length; index++){
if(0 == (pFlag[data[index] >> 3] & (1 << (data[index] % 8))))
printf("%d\n", index);
}
free(pFlag);
return;
} 为了多核的并行计算，我们添加了子函数_get_lost，我们进一步补充完整。
copy to clipboardprint typedef struct _RANGE
{
int start;
int end;
}RANGE;
void _get_lost_number(int data[], int start, int end, unsigned char pFlag[])
{
int index;
for(index = start; index < end; index++){
if(0 == (pFlag[data[index] >> 3] & (1 << (data[index] % 8))))
pFlag[data[index] >> 3] |= 1 << (data[index] % 8);
}
}
typedef struct _RANGE
{
int start;
int end;
}RANGE;
void _get_lost_number(int data[], int start, int end, unsigned char pFlag[])
{
int index;
for(index = start; index < end; index++){
if(0 == (pFlag[data[index] >> 3] & (1 << (data[index] % 8))))
pFlag[data[index] >> 3] |= 1 << (data[index] % 8);
}
}
工作总结：
（1）代码的优化是可以不断进行得，但是不见得适用于所有的场景
（2）目前的cpu已经开始从2核->4核->8核转变，朋友们在可能的情况下尽量多掌握一些多核编程的知识。