(l,r]找low
class Solution {
public:
int searchInsert(vector<int>& nums, int target) {
vector<int> ans;
int l = -1, r = (int)nums.size()-1;
while (l < r) {
int mid = (l + r+1) >> 1;
if (nums[mid] < target) l = mid;
else r = mid - 1;
}
return ++l;
}
};