Find First and Last Position of Element in Sorted Array

 

Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.

If target is not found in the array, return [-1, -1].

 

Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]

 class Solution {
public:
    vector<int> searchRange(vector<int>& v, int b) {
        int n=v.size();
        int low=0;
        int high=n-1;
        int mid;
        vector<int> ans(2);
        ans[0]=-1;
        ans[1]=-1;
        while(low<=high)
        {
            mid=low+(high-low)/2;
            if(v[mid]==b)
            {
                ans[0]=mid;
                high=mid-1;
            }
            else if(v[mid]<b){
                low=mid+1;
            }
            else{
                high=mid-1;
            }
        }
        if(ans[0]==-1) return ans;
         low=ans[0];
         high=n-1;
        while(low<=high)
        {
            mid=low+(high-low)/2;
            if(v[mid]==b)
            {
                ans[1]=mid;
                low=mid+1;
            }
            else if(v[mid]<b){
                low=mid+1;
            }
            else{
                high=mid-1;
            }
        }
        return ans;
    }
};