As the given array is sorted so we can think of the implementation of binary search.
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#include <iostream>
using namespace std;
int firstocc(vector<int>& nums, int target)
{ int start = 0, end = nums.size()-1, ans=-1;
while(start<=end)
{
int mid = end + (start-end)/2;
if(nums[mid]==target)
{
ans = mid; // got the targeted element here
end = mid-1; //checking for the first occurrence and it will be in left half
}
else if(nums[mid]>target)
end = mid-1;
else
start = mid+1;
}
return ans;
}
int main()
{
vector <int> nums = {1,2,6,6,6,6,8,10} ;
int target = 6;
int ans = firstocc( nums, target );
cout<< "First occurrence of " << target << "is at index " << ans ;
return 0;
}
output :
First occurrence of 6 is at index 2.