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Search for a Range

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].

 

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 Array Binary Search
 
class Solution {public:    int find(int a[],int left,int right,int key,bool isLeft){        if(left>right)            return -1;        int mid=(right+left)/2;        if(a[mid]==key){            int pos=isLeft ? find(a,left,mid-1,key,isLeft) : find(a,mid+1,right,key,isLeft);            return pos==-1 ? mid : pos;         }else if(a[mid]>key)            return find(a,left,mid-1,key,isLeft);        else            return find(a,mid+1,right,key,isLeft);    }    vector<int> searchRange(int A[], int n, int target) {        int pos1=find(A,0,n-1,target,true);        int pos2=find(A,0,n-1,target,false);        vector<int> range;        range.push_back(pos1);        range.push_back(pos2);        return range;    }};

 

Search for a Range