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6. Search Insert Position

easyAsked at Booking

Binary-search the insertion index — Booking probes this to confirm you can position a new price into a sorted dynamic-pricing curve.

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

Problem

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

Constraints

  • 1 <= nums.length <= 10^4
  • nums contains distinct values sorted ascending

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

Scan until you find an element >= 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

Standard binary search; when not found, lo is the insertion point.

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:

Booking-specific tips

Booking will appreciate if you frame the array as a sorted dynamic-pricing ladder and binary search as the way to slot a new nightly rate in O(log n).

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Output

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