leetcode——Search for a Range 排序数组中寻找目标下标范围（AC）

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return 

[-1, -1]

.

For example,

Given 

[5, 7, 7, 8, 8, 10]

 and target value 8,

return 

[3, 4]

.

class Solution {
public:
vector<int> searchRange(int A[], int n, int target) {
assert(A!=NULL && n!=0);
vector<int> result;
int start = 0, end = n-1, mid;
while(start <= end)
{
mid = (start+end)/2;
if(A[mid] == target)
{
while(mid>=0 && A[mid]==target)
mid--;
result.push_back(++mid);
while(mid<=n-1 && A[mid]==target)
mid++;
result.push_back(--mid);
return result;
}
else if(A[mid] < target)
start = mid+1;
else
end = mid-1;
}
result.push_back(-1);
result.push_back(-1);
return result;
}
};