initial commit

Author: AMGOcyber123

01.two_sum.cpp

@@ -0,0 +1,28 @@
+class Solution {
+public:
+    vector<int> twoSum(vector<int>& nums, int target) {
+        int n = nums.size();
+        vector<int> store;
+        unordered_map<int,int> s;
+        for(int i = 0; i < n; i++)
+        {
+            /*
+                -> create a hashmap to store 
+                -> nums[i] = complement or target - nums[i];
+                -> store initial index 
+                -> find if complement present in array
+                -> yes , store its index and current i 's  index
+                -> return   
+            */
+            int complement = target-nums[i];
+            if(s.find(complement) != s.end())
+            {
+                store.push_back(s[complement]);
+                store.push_back(i);
+                return store;
+            }
+            s[nums[i]] = i;
+        }
+        return store;
+    }
+};

02.add_two_number.cpp

@@ -0,0 +1,24 @@
+class Solution {
+public:
+  ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
+    ListNode dummy(0);
+    ListNode* p = &dummy;
+    int carry = 0, sum;
+    while(l1 || l2) {
+      sum = carry;
+      if(l1) sum += l1->val;
+      if(l2) sum += l2->val;
+      if(sum >= 10) {
+        carry = sum / 10;
+        sum %= 10;
+      } else carry = 0;
+      p->next = new ListNode(sum);
+      p = p->next;
+      if(l1) l1 = l1->next;
+      if(l2) l2 = l2->next;
+    }
+    if(carry)
+      p->next = new ListNode(carry);
+    return dummy.next;
+  }
+};