35. Search Insert Position

Given a sorted array 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 may assume no duplicates in the array.

Example 1:

Input: [1,3,5,6], 5
Output: 2

Example 2:

Input: [1,3,5,6], 2
Output: 1

Example 3:

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

Example 4:

Input: [1,3,5,6], 0
Output: 0

// STL lower_bound
int searchInsert(vector<int>& nums, int target) { // time: O(logn); space: O(1)
    return lower_bound(nums.begin(), nums.end(), target) - nums.begin();
}

// Binary Search
int searchInsert(vector<int>& nums, int target) { // time: O(logn); space: O(1)
    int left = 0, right = nums.size();
    while (left < right) {
        int mid = left + (right - left) / 2;
        if (nums[mid] < target) {
            left = mid + 1;
        } else right = mid;
    }
    return left;
}