Fisher–Yates洗牌算法
https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle
void ShuffleArray_Fisher_Yates(char* arr, int len)
{
int i = len, j;
char temp;
if ( i == 0 ) return;
while ( --i ) {
j = rand() % (i+1);
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
}
很简洁却很重要的