day 9

Author: sachuverma

Leetcode Daily Challenge/August-2021/09. Add Strings.cpp

@@ -0,0 +1,55 @@
+/*
+Add Strings
+===========
+
+Given two non-negative integers, num1 and num2 represented as string, return the sum of num1 and num2 as a string.
+
+You must solve the problem without using any built-in library for handling large integers (such as BigInteger). You must also not convert the inputs to integers directly.
+
+Example 1:
+Input: num1 = "11", num2 = "123"
+Output: "134"
+
+Example 2:
+Input: num1 = "456", num2 = "77"
+Output: "533"
+
+Example 3:
+Input: num1 = "0", num2 = "0"
+Output: "0"
+ 
+Constraints:
+1 <= num1.length, num2.length <= 104
+num1 and num2 consist of only digits.
+num1 and num2 don't have any leading zeros except for the zero itself.
+*/
+
+class Solution
+{
+public:
+    string addStrings(string num1, string num2)
+    {
+        reverse(num1.begin(), num1.end());
+        reverse(num2.begin(), num2.end());
+
+        string ans = "";
+        int carry = 0, i = 0;
+
+        while (i < num1.size() || i < num2.size() || carry)
+        {
+            int a = (i < num1.size() ? num1[i] - '0' : 0);
+            int b = (i < num2.size() ? num2[i] - '0' : 0);
+
+            int sum = a + b + carry;
+            int digit = sum % 10;
+
+            ans.push_back(digit + '0');
+            carry = sum / 10;
+
+            i++;
+        }
+
+        reverse(ans.begin(), ans.end());
+        return ans;
+    }
+};

Leetcode Daily Challenge/August-2021/README.md

@@ -10,3 +10,4 @@
 | 5.  | [Stone Game](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/613/week-1-august-1st-august-7th/3870/)           |       [cpp](./05.%20Stone%20Game.cpp)       |
 | 6.  | [N-ary Tree Level Order Traversal](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/613/week-1-august-1st-august-7th/3871/)           |       [cpp](./06.%20N-ary%20Tree%20Level%20Order%20Traversal.cpp)       |
 | 7.  | [Palindrome Partitioning II](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/613/week-1-august-1st-august-7th/3872/)           |       [cpp](./07.%20Palindrome%20Partitioning%20II.cpp)       |
+| 9.  | [Add Strings](https://leetcode.com/explore/challenge/card/august-leetcoding-challenge-2021/614/week-2-august-8th-august-14th/3875/)           |       [cpp](./09.%20Add%20Strings.cpp)       |