数字在排序数组中出现的次数
C++，二分。
class Solution {
public:
int GetNumberOfK(vector<int> data ,int k) {
int index = Find(data, k);
if (index == -1) return 0;
int left = index, right = index;
for (; left >= 0 && data[left] == k; left--) ;
for (; right < data.size() && data[right] == k; right++) ;
return right - left - 1;
}
int Find(vector<int> &data, int &k) {
int ans = -1;
int left = 0, right = data.size() - 1;
int mid = (left + right) / 2;
while (left <= right) {
mid = (left + right) / 2;
if (k > data[mid])
left = mid + 1;
else if (k < data[mid])
right = mid - 1;
else {
ans = mid;
break;
}
}
return ans;
}
};
