35. Search Insert Position

1. Description

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.
You must write an algorithm with O(log n) runtime complexity.

2. Example

Example 1

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

Example 2

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

Example 3

Input: nums = [1,3,5,6], target = 7
Output: 4

3. Constraints

• 1 <= nums.length <= $10^4$
• $-10^4$ <= nums[i] <= $10^4$
• nums contains distinct values sorted in ascending order.
• $-10^4$ <= target <= $10^4$

4. Solutions

Binary Search

n = nums.size()
Time complexity : O(logn)
Space complexity : O(1)

class Solution {
public:
    int searchInsert(const vector<int> &nums, int target) {
        int left = 0, right = nums.size();
        while (left < right) {
            int middle = left + (right - left) / 2;
            if (nums[middle] < target) {
                left = middle + 1;
            } else {
                right = middle;
            }
        }

        return left;
    }
};