Binary Search: the idea to remember.

The core insight

Keep a closed candidate interval and discard the midpoint after a failed comparison.

Why it works

If the target exists it remains inside [left, right]. Each failed comparison strictly shortens the interval.

The mistake to avoid

Using left = mid can stall on a two element interval.

Commented Java solution

Use java.util.* imports and a surrounding solution class. Tree snippets assume the standard TreeNode definition; linked lists use ListNode and Clone Graph uses a Node with val and neighbors; Copy Random List uses Node with val, next and random. Read the input assumptions above.

int search(int[] nums, int target) {
    int left = 0, right = nums.length - 1;
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (nums[mid] == target) return mid;
        if (nums[mid] < target) left = mid + 1;
        else right = mid - 1;
    }
    return -1;
}

Make the next connection