Find First and Last Position of Element in Sorted Array | LeetCode | Java

#leetcode #java #binarysearch #algorithms

In this problem, we would be applying the two binary search to check whether the target element is present or not. If present, we would be moving the pointers forward & backward to find the occurrence of the element (first & last).

class Solution {
    public int[] searchRange(int[] nums, int target) {

        int res[] = {-1, -1};

        int n = nums.length;

        int low = 0, high = n-1;

        while(low<=high){

            int mid = low + (high-low)/2;

            if(nums[mid]==target){
                res[0] = mid;
                high = mid-1;
            }

           else if(nums[mid]<target)
                low = mid+1;

            else
                high = mid-1;
        }

        low = 0;
        high = n-1;

        while(low<=high){

            int mid = low + (high-low)/2;

            if(nums[mid]==target){
                res[1] = mid;
                low = mid+1;
            }

           else if(nums[mid]<target)
                low = mid+1;

            else
                high = mid-1;
        }

        return res;
    }
}