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| 1 | +--- |
| 2 | +id: search-insert-position |
| 3 | +title: Search Insert Position |
| 4 | +difficulty: Easy |
| 5 | +sidebar_label: 0038-SearchInsertPosition |
| 6 | +tags: |
| 7 | + - Array |
| 8 | + - Binary Search |
| 9 | +--- |
| 10 | + |
| 11 | +## Problem Description |
| 12 | + |
| 13 | +| Problem Statement | Solution Link | LeetCode Profile | |
| 14 | +| :---------------- | :------------ | :--------------- | |
| 15 | +| [Merge Two Sorted Lists](https://leetcode.com/problems/search-insert-position/) | [Merge Two Sorted Lists Solution on LeetCode](https://leetcode.com/problems/search-insert-position/solutions/) | [VijayShankerSharma](https://leetcode.com/u/darkknight648/) | |
| 16 | + |
| 17 | +## Problem Description |
| 18 | + |
| 19 | +Given a sorted array `nums` 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. |
| 20 | + |
| 21 | +You must write an algorithm with O(log n) runtime complexity. |
| 22 | + |
| 23 | +### Examples |
| 24 | + |
| 25 | +#### Example 1: |
| 26 | + |
| 27 | +- **Input:** |
| 28 | + - `nums = [1,3,5,6]` |
| 29 | + - `target = 5` |
| 30 | +- **Output:** `2` |
| 31 | + |
| 32 | +#### Example 2: |
| 33 | + |
| 34 | +- **Input:** |
| 35 | + - `nums = [1,3,5,6]` |
| 36 | + - `target = 2` |
| 37 | +- **Output:** `1` |
| 38 | + |
| 39 | +#### Example 3: |
| 40 | + |
| 41 | +- **Input:** |
| 42 | + - `nums = [1,3,5,6]` |
| 43 | + - `target = 7` |
| 44 | +- **Output:** `4` |
| 45 | + |
| 46 | +### Constraints |
| 47 | + |
| 48 | +- `1 <= `nums.length` <= 10^4` |
| 49 | +- `-10^4 <= `nums[i]` <= 10^4` |
| 50 | +- `nums` contains distinct values sorted in ascending order. |
| 51 | +- `-10^4 <= `target` <= 10^4` |
| 52 | + |
| 53 | +### Approach |
| 54 | + |
| 55 | +To solve the problem with O(log n) runtime complexity, we can use binary search to find the insertion position of the target value. |
| 56 | + |
| 57 | +1. **Binary Search:** |
| 58 | + - Start with low = 0 and high = length of `nums` - 1. |
| 59 | + - While `low <= high`, compute mid as (low + high) / 2. |
| 60 | + - If the target value is equal to the value at index mid, return mid. |
| 61 | + - If the target value is less than the value at index mid, set high = mid - 1. |
| 62 | + - If the target value is greater than the value at index mid, set low = mid + 1. |
| 63 | + - After the loop, if the target value is not found, return low (or high + 1). |
| 64 | + |
| 65 | +### Solution Code |
| 66 | + |
| 67 | +#### Python |
| 68 | + |
| 69 | +``` |
| 70 | +class Solution(object): |
| 71 | + def searchInsert(self, nums, target): |
| 72 | + left, right = 0, len(nums) - 1 |
| 73 | + |
| 74 | + while left <= right: |
| 75 | + mid = left + (right - left) // 2 |
| 76 | + if nums[mid] == target: |
| 77 | + return mid |
| 78 | + elif nums[mid] < target: |
| 79 | + left = mid + 1 |
| 80 | + else: |
| 81 | + right = mid - 1 |
| 82 | + |
| 83 | + return left |
| 84 | +
|
| 85 | +``` |
| 86 | + |
| 87 | +#### Java |
| 88 | + |
| 89 | +``` |
| 90 | +class Solution { |
| 91 | + public int searchInsert(int[] nums, int target) { |
| 92 | + int low = 0, high = nums.length - 1; |
| 93 | + |
| 94 | + while (low <= high) { |
| 95 | + int mid = low + (high - low) / 2; |
| 96 | + if (nums[mid] == target) { |
| 97 | + return mid; |
| 98 | + } else if (nums[mid] < target) { |
| 99 | + low = mid + 1; |
| 100 | + } else { |
| 101 | + high = mid - 1; |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + return low; |
| 106 | + } |
| 107 | +} |
| 108 | +``` |
| 109 | + |
| 110 | +#### C++ |
| 111 | + |
| 112 | +``` |
| 113 | +class Solution { |
| 114 | +public: |
| 115 | + int searchInsert(vector<int>& nums, int target) { |
| 116 | + int low = 0, high = nums.size() - 1; |
| 117 | + |
| 118 | + while (low <= high) { |
| 119 | + int mid = low + (high - low) / 2; |
| 120 | + if (nums[mid] == target) { |
| 121 | + return mid; |
| 122 | + } else if (nums[mid] < target) { |
| 123 | + low = mid + 1; |
| 124 | + } else { |
| 125 | + high = mid - 1; |
| 126 | + } |
| 127 | + } |
| 128 | + |
| 129 | + return low; |
| 130 | + } |
| 131 | +}; |
| 132 | +``` |
| 133 | + |
| 134 | +### Conclusion |
| 135 | + |
| 136 | +The above solution efficiently finds the insertion position of a target value in a sorted array using binary search. It achieves a runtime complexity of O(log n), providing an optimal solution to the problem. |
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