Cross number puzzle

You and your friends are solving a puzzle called the crossnumber puzzle. Here the task is to reach the destination by spending a minimum number of coins. You are placed initially at zero, here at $I^{th}$ step you can move i steps either to the left or right by spending i coins. Return the minimum number of coins you need to spend to reach the destination.

Function description

Complete the solve$()$ function. This function takes the following argument and returns $1$ if the string word is valic else return $0$ :

N$.$ Represents the target

Input format for custom testing

Note: Use this input format if you are testing against custom input or writing code in a language where we don't provide