*Binary Search

For a given sorted array (ascending order) and a target number, find the first index of this number in O(log n) time complexity.

If the target number does not exist in the array, return -1.

 

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Example

If the array is [1, 2, 3, 3, 4, 5, 10], for given target 3, return 2.

Challenge

If the count of numbers is bigger than 2^32, can your code work properly?

    public int binarySearch(int[] nums, int target) 
    {
        //write your code here
        if(nums.length==0)return -1;
        int left = 0;
        int right = nums.length-1;
        while(left+1 <right)
        {
            int mid = (left + right) /2;
            if(target==nums[mid])
            {
                right = mid;
            }
            
            if(target<nums[mid])
            {
                right = mid-1;
            }
            if(target>nums[mid])
            {
                left = mid+1;
            }
            
        }
        
        if(nums[left]==target) return left;
        if(nums[right]==target) return right;
        return -1;
    }