BuildArray-LCQ.cpp

/*
Build an Array With Stack Operations

You are 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": Reads a new element from the beginning list, and pushes it in the array.
"Pop": Deletes the last element of the array.
If the target array is already built, stop reading more elements.
Return a list of the operations needed to build target. The test cases are generated so 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 -> [1]
Read number 2 and automatically push in the array then Pop it -> [1]
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.


Constraints:

1 <= target.length <= 100
1 <= n <= 100
1 <= target[i] <= n
target is strictly increasing.
*/


class Solution {
public:
	vector<string> buildArray(vector<int>& target, int n) {
		vector<string>res;
		int index = 0, value = 1;
		while (index < target.size()) {
			res.push_back("Push");
			if (target[index] == value) {
				index++;
			}
			else
				res.push_back("Pop");
			value++;
		}
		return res;
	}
};