剑指offer——面试题29：数组中出现次数超过一半的数字

int MoreThanHalfNum_Solution1(int* numbers, int length)
{
if(CheckInvalidArray(numbers, length))
return 0;

int middle = length >> 1;
int start = 0;
int end = length - 1;
int index = Partition(numbers, length, start, end);
while(index != middle)
{
if(index > middle)
{
end = index - 1;
index = Partition(numbers, length, start, end);
}
else
{
start = index + 1;
index = Partition(numbers, length, start, end);
}
}

int result = numbers[middle];
if(!CheckMoreThanHalf(numbers, length, result))
result = 0;

return result;
}



bool CheckInvalidArray(int* numbers, int length)
{
g_bInputInvalid = false;
if(numbers == NULL && length <= 0)
g_bInputInvalid = true;

return g_bInputInvalid;
}

bool CheckMoreThanHalf(int* numbers, int length, int number)
{
int times = 0;
for(int i = 0; i < length; ++i)
{
if(numbers[i] == number)
times++;
}

bool isMoreThanHalf = true;
if(times * 2 <= length)
{
g_bInputInvalid = true;
isMoreThanHalf = false;
}

return isMoreThanHalf;
}



int MoreThanHalfNum_Solution2(int* numbers, int length)
{
if(CheckInvalidArray(numbers, length))
return 0;

int result = numbers[0];
int times = 1;
for(int i = 1; i < length; ++i)
{
if(times == 0)
{
result = numbers[i];
times = 1;
}
else if(numbers[i] == result)
times++;
else
times--;
}

if(!CheckMoreThanHalf(numbers, length, result))
result = 0;

return result;
}