[43. MultiplyStrings] solution by using cstring / string

Author: YILING

LeetCode.xcodeproj/project.pbxproj

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LeetCode/43_Multiply_Strings.cpp

@@ -0,0 +1,27 @@
+//
+//  43_Multiply_Strings.cpp
+//  LeetCode
+//
+//  Created by Yi-Ling Wu on 13/03/2017.
+//  Copyright © 2017 YILING. All rights reserved.
+//
+
+#include "43_Multiply_Strings.hpp"
+
+std::string MultiplyStrings::multiply(std::string num1, std::string num2) {
+    std::string s(1000,'0');
+    reverse(num1.begin(), num1.end());
+    reverse(num2.begin(), num2.end());
+    for(int i = 0; i < num1.length(); i++) {
+        for(int j = 0;j < num2.length(); j++) {
+            int temp = (num1[i] - '0') * (num2[j] - '0');
+            s[i+j+1] = s[i+j+1] - '0' + (s[i+j] - '0' + temp) / 10 + '0';
+            s[i+j] = (s[i+j] - '0'+ temp) % 10 + '0';
+        }
+    }
+    reverse(s.begin(),s.end());
+    if(s.find_first_not_of('0') == std::string::npos)
+        return "0";
+    else
+        return s.substr(s.find_first_not_of('0'));
+}

LeetCode/43_Multiply_Strings.hpp

@@ -0,0 +1,21 @@
+//
+//  43_Multiply_Strings.hpp
+//  LeetCode
+//
+//  Created by Yi-Ling Wu on 13/03/2017.
+//  Copyright © 2017 YILING. All rights reserved.
+//
+
+#ifndef _3_Multiply_Strings_hpp
+#define _3_Multiply_Strings_hpp
+
+#include <stdio.h>
+#include <cstring>
+#include <string>
+
+// Ref: http://blog.csdn.net/nk_test/article/details/48912763
+class MultiplyStrings {
+public:
+    std::string multiply(std::string num1, std::string num2);
+};
+#endif /* _3_Multiply_Strings_hpp */

LeetCode/main.cpp

@@ -7,15 +7,25 @@
 //
 
 #include <iostream>
+#include <cstring>
+#include <string>
 #include "1_two_sum.hpp"
+#include "43_Multiply_Strings.hpp"
 
 int main(int argc, const char * argv[]) {
 
     // Test_1: TwoSum
-    TwoSum *twosum = new TwoSum;
+    /*TwoSum *twosum = new TwoSum;
     std::vector<int> nums = {3,2,4};
     int target = 6;
     std::vector<int> result = twosum->twoSum(nums, target);
     return 0;
-    
+     */
+
+    // Teset_2:
+    MultiplyStrings *mutiplyString = new MultiplyStrings;
+    std::string num1 = "29292999";
+    std::string num2 = "329393939";
+    std::string result = mutiplyString->multiply(num1, num2);
+    return 0;
 }