# 2022-05-17

## [283. Move Zeroes](https://leetcode.com/problems/move-zeroes/)

### Description

Given an integer array `nums`, move all `0`'s to the end of it while maintaining the relative order of the non-zero elements.

**Note** that you must do this in-place without making a copy of the array.

**Example 1:**

```
Input: nums = [0,1,0,3,12]
Output: [1,3,12,0,0]
```

**Example 2:**

```
Input: nums = [0]
Output: [0]
```

**Constraints:**

* `1 <= nums.length <= 104`
* `-231 <= nums[i] <= 231 - 1`

**Follow up:** Could you minimize the total number of operations done?

### Solution

```go
func moveZeroes(nums []int) {
    for i, j := 0, 0; j < len(nums); {
        if nums[j] != 0 {
            nums[i], nums[j] = nums[j], nums[i]
            i++
        }
        j++
    }
}
```

## [167. Two Sum II - Input Array Is Sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/)

### Description

Given a **1-indexed** array of integers `numbers` that is already ***sorted in non-decreasing order***, find two numbers such that they add up to a specific `target` number. Let these two numbers be `numbers[index1]` and `numbers[index2]` where `1 <= index1 < index2 <= numbers.length`.

Return *the indices of the two numbers,* `index1` *and* `index2`*, **added by one** as an integer array* `[index1, index2]` *of length 2.*

The tests are generated such that there is **exactly one solution**. You **may not** use the same element twice.

Your solution must use only constant extra space.

**Example 1:**

```
Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore, index1 = 1, index2 = 2. We return [1, 2].
```

**Example 2:**

```
Input: numbers = [2,3,4], target = 6
Output: [1,3]
Explanation: The sum of 2 and 4 is 6. Therefore index1 = 1, index2 = 3. We return [1, 3].
```

**Example 3:**

```
Input: numbers = [-1,0], target = -1
Output: [1,2]
Explanation: The sum of -1 and 0 is -1. Therefore index1 = 1, index2 = 2. We return [1, 2].
```

**Constraints:**

* `2 <= numbers.length <= 3 * 104`
* `-1000 <= numbers[i] <= 1000`
* `numbers` is sorted in **non-decreasing order**.
* `-1000 <= target <= 1000`
* The tests are generated such that there is **exactly one solution**.

### Solution

#### Approach #0

```go
func twoSum(numbers []int, target int) []int {
    for i := 0; i < len(numbers); i++ {
        for j := i + 1; j < len(numbers); j++ {
            if numbers[i]+numbers[j] == target {
                return []int{i + 1, j + 1}
            }
        }
    }
    return []int{}
}
```

#### Approach #1

```go
func twoSum(numbers []int, target int) []int {
    for i, j := 0, len(numbers)-1; i < j; {
        sum := numbers[i] + numbers[j]
        if sum == target {
            return []int{i + 1, j + 1}
        }
        if sum > target {
            j--
        } else {
            i++
        }

    }
    return []int{}
}
```