C++二分标准模板：
二分查找
http://www.nowcoder.com/questionTerminal/7bc4a1c7c371425d9faa9d1b511fe193
C++二分标准模板
class Solution {
public:
int upper_bound_(int n, int v, vector<int>& a) {
int l = 0, r = n;
while(l < r) {
int mid = l + r >> 1;
if(a[mid] < v) l = mid + 1;
else r = mid;
}
return l + 1;
}
};