Implementation of C lower_bound

Question

Based on the following definition found here

Returns an iterator pointing to the first element in the sorted range [first,last) which does not com

Answer 1

Example if this is the given array

1 2 3 3 4

and different values of x is

3 then firstOccurance will be 2 and lastOccurance will be 3

2 then firstOccurance will be 1 and lastOccurance will be 1

10 then firstOccurance will be -1 and lastOccurance will be -1

int firstOccurance(vector& arr, int x){
        int low = 0;
        int high = arr.size();
        int ans=-1;
        while(low<=high){
            int mid = (low+high)/2;
            if(arr[mid]==x)     ans=mid;
            if(arr[mid]>=x)     high=mid-1;
            else    low = mid+1;
        }
        return ans;
    }


int lastOccurance(vector& arr, int x){
    int low = 0;
    int high = arr.size();
    int ans=-1;
    while(low<=high){
        int mid = (low+high)/2;
        if(arr[mid]==x)     ans=mid;
        if(arr[mid]<=x)     low=mid+1;
        else    high = mid-1;
    }
    return ans;
}