# LeetCode – Stack – Build an Array With Stack Operations

Given an array `target` and an integer `n`. In each iteration, you will read a number from  `list = {1,2,3..., n}`.

Build the `target` array using the following operations:

• Push: Read a new element from the beginning `list`, and push it in the array.
• Pop: delete the last element of the array.
• If the target array is already built, stop reading more elements.

You are guaranteed that the target array is strictly increasing, only containing numbers between 1 to `n` inclusive.

Return the operations to build the target array.

You are guaranteed that the answer is unique.

Example 1:

```Input: target = [1,3], n = 3
Output: ["Push","Push","Pop","Push"]
Explanation:
Read number 1 and automatically push in the array -> 
Read number 2 and automatically push in the array then Pop it -> 
Read number 3 and automatically push in the array -> [1,3]
```

Example 2:

```Input: target = [1,2,3], n = 3
Output: ["Push","Push","Push"]
```

Example 3:

```Input: target = [1,2], n = 4
Output: ["Push","Push"]
Explanation: You only need to read the first 2 numbers and stop.
```

Example 4:

```Input: target = [2,3,4], n = 4
Output: ["Push","Pop","Push","Push","Push"]```
``class Solution {    public List<String> buildArray(int[] target, int n) {        int i=0;        int j=1;        List<String> stackOps = new ArrayList<String>();        while(j<=n){            if(i == target.length) break;            if(target[i] == j){               stackOps.add("Push");               i++;            }else{                stackOps.add("Push");                stackOps.add("Pop");            }            j++;        }        return stackOps;    }}``