/
38_NumbersOfK.cpp
63 lines (53 loc) · 1.56 KB
/
38_NumbersOfK.cpp
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class Solution {
public:
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 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);
}
int getLastK(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 < data.size()-1 && data[midIndex+1] != k || midIndex == data.size()-1)
return midIndex;
else
start = midIndex+1;
}
else if(midData > k)
end = midIndex-1;
else
start = midIndex+1;
return getLastK(data,k,start,end);
}
};