diff --git a/C++/Solution#3.cpp b/C++/Solution#3.cpp
new file mode 100644
index 0000000..6f41765
--- /dev/null
+++ b/C++/Solution#3.cpp
@@ -0,0 +1,46 @@
+/*
+3. Longest Substring Without Repeating Characters
+Medium
+
+
+Given a string s, find the length of the longest substring without repeating characters.
+
+ 
+
+Example 1:
+
+Input: s = "abcabcbb"
+Output: 3
+Explanation: The answer is "abc", with the length of 3.
+Example 2:
+
+Input: s = "bbbbb"
+Output: 1
+Explanation: The answer is "b", with the length of 1.
+
+*/
+
+class Solution {
+public:
+    int lengthOfLongestSubstring(string s) {
+        int beg=0;
+        int end=0;
+        unsigned long int len=0;
+        set<char> st;
+        while(end<s.length())
+        {
+            if(!(st.count(s[end])))
+            {
+                st.insert(s[end]);
+                len=max(st.size(),len);
+                end++;
+            }
+            else
+            {
+                st.erase(s[beg]);
+                beg++;
+            }
+        }
+        return len;
+    }
+};
\ No newline at end of file
diff --git a/C++/Solution#42.cpp b/C++/Solution#42.cpp
new file mode 100644
index 0000000..fa21316
--- /dev/null
+++ b/C++/Solution#42.cpp
@@ -0,0 +1,57 @@
+/*
+42. Trapping Rain Water
+Hard
+
+Example 1:
+
+
+Input: height = [0,1,0,2,1,0,1,3,2,1,2,1]
+Output: 6
+Explanation: The above elevation map (black section) is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped.
+Example 2:
+
+Input: height = [4,2,0,3,2,5]
+Output: 9
+
+*/
+
+class Solution {
+public:
+    int trap(vector<int>& height) {
+        if(height.size()==0)
+            return 0;
+        int i,pi=0,wt=0,s=(int)(height.size()-1),tp=0;
+        int p=height[0];
+        for(i=1;i<=s;i++)
+        {
+            if(height[i]>p)
+            {
+                pi=i;
+                p=height[i];
+                tp=0;
+            }
+            else
+            {
+                wt+=p-height[i];
+                tp+=p-height[i];
+            }
+        }
+        if(pi<s)
+        {
+            wt-=tp;
+            p=height[s];
+            for(i=s-1;i>=pi;i--)
+            {
+                if(height[i] >= p)
+                {
+                  p = height[i];
+                } 
+                else
+                {
+                  wt += p - height[i];
+                }
+            }
+        }
+        return wt;
+    }
+};
\ No newline at end of file
diff --git a/Contributors.md b/Contributors.md
index efcf8ce..3f8c58f 100644
--- a/Contributors.md
+++ b/Contributors.md
@@ -29,3 +29,5 @@
 
 **Caitlin Genna** --> "CS Computer Science Graduate, Fordham University." --> [caitlingenna](https://github.com/caitlingenna)
 
+**Utkarsh Nigam** --> "Learner | C.S undergrad" --> [utkarsh-7](https://github.com/utkarsh-7)
+