Task1TS.js

// Gets the input file's contents
function getInput() {
    var fs = require("fs");
    var inputContent = fs.readFileSync(".\\Task 2. Input (1).txt", "utf-8", function (err) {
        if (err) {
            throw err;
        }
    });
    return inputContent; // returns input file contents
}
// Checks if the character is upperCase
function isUpperCase(char) {
    return char === char.toUpperCase();
}
// Subtracts the unwanted pair of characters
function removeByIndex(str, index) {
    if (index === 0) {
        return str.slice(2);
    }
    else {
        return str.substring(0, index) + str.substring(index + 2, str.length);
    }
}
// Finds how many units of polymer remain after reaction
function findUnits() {
    try {
        var input = getInput();
        var count = 0; // count how many reactions occured
        for (var index = 0; index < input.length; index++) {
            // if reaction occurs at index 0 or 1, the index will be negative
            if (index < 0 && input.length > 0) {
                index = 0;
            }
            // Check if it's the last index.
            if (index === input.length - 1) {
                break;
            }
            else {
                // Adjacent characters
                var first = input[index];
                var second = input[index + 1];
                // Check if characters match
                if (first.toLowerCase() === second.toLowerCase()) {
                    // Check character polarity
                    var UpperFirst = isUpperCase(first);
                    var UpperSecond = isUpperCase(second);
                    // If only one of them are uppercase, reaction occurs
                    if ((UpperFirst && UpperSecond === false) ||
                        (UpperFirst === false && UpperSecond)) {
                        input = removeByIndex(input, index);
                        count++;
                        index = index - 2; // set loop to -2 positions from the beginning to find newly formed polarities
                    }
                }
            }
        }
        console.log("Polarity units remaining:", input.length, "\nNumber of reactions occured: ", count);
    }
    catch (error) {
        console.log(error);
    }
}
findUnits();