/*
*N+2个数,N个数出现了偶数次,
*2个数出现了奇数次(这两个数不相等),问用O(1)的空间复杂度,
*找出这两个数,不需要知道具体位置,只需要知道这两个值。
*/
#include<iostream>
using namespace std;
//判断indexBit位上是否为1
bool IsBit1(int num, unsigned int indexBit)
{
num = num >> indexBit;
return (num & 1);
}
//找到num第一个为1的位
unsigned int FindFirstBitIs1(int num)
{
int indexBit = 0;
while(((num&1)==0)&&(indexBit < 8 * sizeof(int)))
{
num = num >> 1;
++indexBit;
}
return indexBit;
}
void FindNumsApperOnce(int data[], int length, int* num1, int* num2)
{
if(data==NULL || length < 2)
{
return;
}
int resultEOR = 0;
for(int i=0; i < length; ++i)
{
resultEOR ^= data[i];
}
*num1 = *num2 = 0;
unsigned int indexOf1 = FindFirstBitIs1(resultEOR);
for(int i=0; i<length; ++i)
{
if(IsBit1(data[i], indexOf1))
{
*num1 ^= data[i];
}
else
{
*num2 ^= data[i];
}
}
}
int main()
{
int data[] = {2,4,3,6,3,2,5,5};
int num1 = -1;
int num2 = -1;
FindNumsApperOnce(data,8,&num1,&num2);
cout << "数组之中只出现一次的数字是: " << num1 << ", " << num2;
}