43. Multiply Strings

Author: coderbean

src/leetcode/_43_/Main.java

@@ -0,0 +1,12 @@
+package leetcode._43_;
+
+/**
+ * Created by zhangbo54 on 2019-03-04.
+ */
+public class Main {
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println(solution.multiply("123", "456"));
+    }
+}
+

src/leetcode/_43_/Solution.java

@@ -0,0 +1,9 @@
+package leetcode._43_;
+
+import java.math.BigDecimal;
+
+class Solution {
+    public String multiply(String num1, String num2) {
+        return new BigDecimal(num1).multiply(new BigDecimal(num2)).toString();
+    }
+}

src/leetcode/_43_/solution.md

@@ -0,0 +1,42 @@
+### [43\. Multiply StringsCopy for MarkdownCopy for Markdown](https://leetcode.com/problems/multiply-strings/)
+
+Difficulty: **Medium**
+
+
+Given two non-negative integers `num1` and `num2` represented as strings, return the product of `num1` and `num2`, also represented as a string.
+
+**Example 1:**
+
+```
+Input: num1 = "2", num2 = "3"
+Output: "6"```
+
+**Example 2:**
+
+```
+Input: num1 = "123", num2 = "456"
+Output: "56088"
+```
+
+**Note:**
+
+1.  The length of both `num1` and `num2` is < 110.
+2.  Both `num1` and `num2` contain only digits `0-9`.
+3.  Both `num1` and `num2` do not contain any leading zero, except the number 0 itself.
+4.  You **must not use any built-in BigInteger library** or **convert the inputs to integer** directly.
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+import java.math.BigDecimal;
+​
+class Solution {
+    public String multiply(String num1, String num2) {
+        return new BigDecimal(num1).multiply(new BigDecimal(num2)).toString();
+    }
+}
+```
+![](https://ws2.sinaimg.cn/large/006tKfTcgy1g1h7hkk2idj310m0oyjv9.jpg)