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]
.
二分查找
class Solution { public: int begin = -1, end = -1; vectorsearchRange(int A[], int n, int target) { vector ans; find(A,0,n-1,target); ans.push_back(begin); ans.push_back(end); return ans; } void find(int A[], int l, int r, int target){ if(l > r) return ; int mid = (l+r) >> 1; if(A[mid] == target){ if(begin == -1 || begin > mid) begin = mid; end = max(mid, end); find(A,l,mid-1,target); find(A,mid+1,r,target); } else if(A[mid] < target) find(A,mid+1,r,target); else find(A,l,mid-1,target); } };