Skip to main content

6. Search Insert Position

easyAsked at Unity

Find the index where a target should be inserted to keep a sorted array sorted. Unity uses this for ordered scene-graph child insertion.

By Alex Chen, Founder, InterviewChamp.AI · Last verified

Problem

Given a sorted array of distinct integers and a target, return the index if found. If not, return the index where it would be inserted to keep order.

Constraints

  • 1 <= nums.length <= 10^4
  • Sorted ascending, distinct

Examples

Example 1

Input
nums=[1,3,5,6], target=5
Output
2

Example 2

Input
nums=[1,3,5,6], target=2
Output
1

Approaches

1. Linear scan

Walk until first index where nums[i] >= target.

Time
O(n)
Space
O(1)
for (let i=0;i<nums.length;i++) if (nums[i] >= target) return i;
return nums.length;

Tradeoff:

2. Binary search lower bound

Maintain [lo,hi]; collapse until lo points at the insertion index.

Time
O(log n)
Space
O(1)
function searchInsert(nums, target) {
  let lo = 0, hi = nums.length;
  while (lo < hi) {
    const mid = (lo + hi) >> 1;
    if (nums[mid] < target) lo = mid + 1;
    else hi = mid;
  }
  return lo;
}

Tradeoff:

Unity-specific tips

Unity wants log-n behavior because ordered child insertion in a scene graph runs every frame and any linear scan is a frame-budget killer.

Solve it now

Free. No sign-up. Python and JavaScript run instantly in your browser.

Output

Press Run or Cmd+Enter to execute

Practice these live with InterviewChamp.AI

Drill Search Insert Position and other Unity interview questions under real-loop conditions with instant feedback on your reasoning, complexity claims, and code.

Practice these live with InterviewChamp.AI →