/********************** 参考代码 ******/
int getFirstK(int* data, int length, int k, int start, int end)
{
if (start > end)
{
return -1;
}
int middleIndex = (start + end) / 2;
int currentData = data[middleIndex];
if (currentData == k)
{
if (middleIndex == 0 || (middleIndex > 0 && data[middleIndex - 1] != k) )
{
return middleIndex;
}
else
{
end = middleIndex - 1;
}
}
else if (currentData > k)
{
end = middleIndex - 1;
}
else
{
start = middleIndex + 1;
}
return getFirstK(data, length, k, start, end);
}
int GetNumberOfK(vector<int> data ,int k) {
int result=0;
if(data.empty())
return 0;
int start = 0;
int end = data.size()-1;
int first = getFirstK(data,k,start,end);
int last = getLastK(data,k,start,end);
if(first >-1 && last >-1)
result = last - first+1;
return result;
}
int getNumbersOfK(int* data, int length, int k)
{
int number = 0;
if (data != NULL && length > 0)
{
int first = getFirstK(data, length, k, 0, length - 1);
int last = getLastK(data, length, k, 0, length - 1);
if (first > -1 && last > -1)
{
number = last - first + 1;
}
}
return number;
}
int getFirstK(vector<int> data, int k, int start, int end)
{
if(start > end)
return -1;
int midIndex = (start + end)/2;
int midData = data[midIndex];
if(midData == k)
{
if(midIndex > 0 && data[midIndex-1] != k || midIndex == 0)
return midIndex;
else
end = midIndex-1;
}
else if(midData > k)
end = midIndex-1;
else
start = midIndex+1;
return getFirstK(data,k,start,end);
}
