feat: Added solution of the given assignment 🚀

Solution.js

@@ -1 +1,64 @@
 // Write your code here
+
+class FixEquation {
+
+    //findMissingDigit: Method for finding the missing digit in the given equation of the format "A * B + C = D";
+    findMissingDigit(string) {
+
+        //extracting the terms from the equation
+        let A = string.slice(0, string.indexOf("*") - 1);
+        let B = string.slice(string.indexOf("*") + 2, string.indexOf("+") - 1);
+        let C = string.slice(string.indexOf("+") + 2, string.indexOf("=") - 1);
+        let D = string.slice(string.indexOf("=") + 2);
+        let result, unknownTerm;
+
+        //Solving the equation for unknown term
+        if (isNaN(A)) {
+            result = String((Number(D) - Number(C)) / Number(B));
+            unknownTerm = A;
+        }
+        else if (isNaN(B)) {
+            result = String((Number(D) - Number(C)) / Number(A));
+            unknownTerm = B;
+        }
+        else if (isNaN(C)) {
+            result = String(Number(A) * Number(B) - Number(D));
+            unknownTerm = C;
+        }
+        else {
+            result = String(Number(A) * Number(B) + Number(C));
+            unknownTerm = D;
+        }
+
+        //checking for valid result and returning correct response
+        if (unknownTerm.length === result.length) {
+            let iq = unknownTerm.indexOf("?");
+            if (result === (unknownTerm.slice(0, iq) + result[iq] + unknownTerm.slice(iq + 1))) {
+                return result[iq]
+            }
+            else return -1;
+        }
+        else {
+            return -1;
+        }
+    }
+}
+
+//sample testcases
+var testCases = [
+    "42 * 47 + 2 = 1?76",
+    "4? * 47 + 2 = 1976",
+    "42 * ?7 + 2 = 1976",
+    "42 * ?47 + 2 = 1976",
+    "2 * 12? + 2 = 247"]
+
+//main starter function
+function main(testCases) {
+    const solution = new FixEquation();
+    testCases.forEach(eq => {
+        console.log(solution.findMissingDigit(eq));
+    });
+}
+
+//main funcion
+main(testCases);