43-Multiply_Strings.java

Java/43-Multiply_Strings.java

@@ -0,0 +1,103 @@
+class Solution {
+
+    public String multiply(String num1, String num2) {
+
+        String finalvalue="";
+
+        if(num1.equals("0")||num2.equals("0"))
+            return "0";
+
+        for(int i= num1.length()-1;i>=0;i--){
+
+           int carry=0;
+	            String finalr="";
+	            int dig1=Integer.parseInt(String.valueOf(num1.charAt(i)));
+
+	            for(int j=num2.length()-1;j>=0;j--){
+	                int dig2=Integer.parseInt(String.valueOf(num2.charAt(j)));
+
+	                int mul = dig1*dig2;
+	                //System.out.println(mul+"m,"+j);
+	                //System.out.println(carry+","+j);
+	                mul=mul+carry;
+
+	                if(j!=0){
+	                	carry=mul/10;
+	                    mul=mul%10;
+
+	                }
+	                finalr=String.valueOf(mul)+finalr;
+
+	            }
+	            //System.out.println(finalr);
+	            //System.out.println(finalvalue);
+	           finalvalue = sum(finalr,finalvalue,num1.length()-1-i);
+
+
+
+	        }
+
+
+
+
+
+        return finalvalue;
+    }
+    public static String sum(String finalr,String finalvalue,int x){
+
+
+
+        String a=finalvalue;
+	        String b=finalr;
+	        String v="";
+	        a = reverse(a);
+	        b = reverse(b);
+
+	        for(int j=1;j<=x;j++){
+
+	            b = "0" + b;
+	        }
+	        //System.out.println(b+"=b");
+	        //addition code
+	        int carry=0;
+	        for(int i=0;i<a.length()||i<b.length();i++)
+	        {
+
+	            int s=0;
+	            //condtions
+	            if(i>=a.length())
+	                s=Integer.parseInt(String.valueOf(b.charAt(i)));
+	            else if(i>=b.length())
+	                s=Integer.parseInt(String.valueOf(a.charAt(i)));
+	            else
+	     s=Integer.parseInt(String.valueOf(a.charAt(i)))+Integer.parseInt(String.valueOf(b.charAt(i)));
+	            s=s+carry;
+	            carry=s/10;
+	            s=s%10;
+
+	            v=v+String.valueOf(s);
+
+	        }
+	        if(carry!=0) {
+
+	        	v=v+String.valueOf(carry);
+
+
+	        }
+	        //System.out.println("v="+reverse(v));
+
+	        return reverse(v);
+
+
+    }
+    public static String reverse(String x)
+    {
+        String f="";
+        for(int i=0;i<x.length();i++){
+            f=x.charAt(i)+f;
+
+        }
+        return f;
+
+    }
+}