feat : solution for symbl.ai GitHub-externship Assignment

Solution.js

@@ -1 +1,123 @@
-// Write your code here
+class FixEquation
+{
+    isPossible(string1, string2)
+    {
+        /*
+            This is the function which gives us desired result, if our solution exists, it 
+            will return that digit, if not then return -1.
+        */
+		let digit = -1;
+
+		if(string1.length !== string2.length) 
+            return digit;
+
+		for(let i=0; i<string1.length; i++)
+        {
+			if(string1[i] !== string2[i] && digit !== -1) 
+                return -1;
+			else if(string1[i] !== string2[i])
+				digit = parseInt(string2[i]);
+		}
+
+		return digit;
+	}
+
+    findMissingDigit(eqn_as_str)
+    {
+        /* 
+            step 1: finding coefficient A, B, C and D from coming equation.
+
+            step 2: then find coefficient In which '?' is present, assume that a variable 
+                    and then calculate that variable by simple math.
+
+            step 3: now compare that calculated variable to given equation coefficient which 
+                    contain '?' by our defined method isPossible()its give result whether 
+                    our solution is possible or not.
+
+            step 4: If solution is possible for given equation, we return that digit which is 
+                    missing, otherwise we return -1. 
+        */
+        let numbers = [] ;
+		let index;
+		let coeff = "" ;
+
+        let i=0;    
+        while( i<eqn_as_str.length)
+        {
+			if(eqn_as_str[i] === '?')
+            {
+				index = numbers.length;
+				coeff+=eqn_as_str[i];
+				i++;
+
+			}
+            else if(eqn_as_str[i] === ' ')
+            {
+				numbers.push(coeff);
+				coeff="";
+				i+=3;
+			}
+            else
+            {
+				coeff+=eqn_as_str[i];
+				i++;
+			}
+		}
+
+        numbers.push(coeff);
+
+        // for finding missing digit
+
+        let possible = true;
+
+        if(index == 0)
+        {
+            let num = parseInt(numbers[3])-parseInt(numbers[2]);
+
+			if(num%parseInt(numbers[1]) === 0)
+            {
+				let ans = num/parseInt(numbers[1]);
+				let res = this.isPossible(numbers[0], ans.toString());
+				return res;
+			}
+            else
+            {
+				possible = false;
+				return -1;
+			}
+        }
+        else if(index == 1)
+        {
+            let num = parseInt(numbers[3])-parseInt(numbers[2]);
+
+			if(num%parseInt(numbers[0]) === 0)
+            {
+				let ans = num/parseInt(numbers[0]);
+				return this.isPossible(numbers[1], ans.toString());
+			}
+            else
+            {
+				possible = false;
+				return -1;
+			}
+        }
+        else if(index == 2)
+        {
+            let num = parseInt(numbers[0])*parseInt(numbers[1]) - parseInt(numbers[3]);
+
+            if(num <= 0) 
+                return -1;
+            else   
+                return this.isPossible(numbers[2], num.toString());
+        }
+        else
+        {
+            let num = parseInt(numbers[0])*parseInt(numbers[1]) + parseInt(numbers[2]);
+
+            if(num <= 0) 
+                return -1;
+            else
+                return this.isPossible(numbers[3], num.toString());      
+        }
+    }
+}