Added LC_4.cpp LC_9.cpp LC_19.cpp LC_22.cpp

Leetcode_Practice_Questions/LC_19.cpp

@@ -0,0 +1,25 @@
+class Solution {
+public:
+    ListNode* removeNthFromEnd(ListNode* head, int n) {
+        ListNode* temp=head;
+        int size=0;
+        while (temp!=nullptr){
+            size++;
+            temp=temp->next;
+        }
+        if (n==1 && size==1) return head->next;
+        if (n==size){
+            ListNode* newHead = head->next;
+            delete head;
+            return newHead;
+        }
+        temp=head;
+        for (int i=0;i<size-n-1;i++){
+            temp=temp->next;
+        }
+        ListNode* res=temp->next;
+        temp->next=temp->next->next;
+        delete res;
+        return head;
+    }
+};

Leetcode_Practice_Questions/LC_22.cpp

@@ -0,0 +1,25 @@
+class Solution {
+public:
+    void backtrack(int o,int c,int n,string& ans,vector<string>& res){
+        if (ans.size()==2*n){
+            res.push_back(ans);
+            return;
+        }
+        if (o<n){
+            ans.push_back('(');
+            backtrack(o+1,c,n,ans,res);
+            ans.pop_back();
+        }
+        if (o>c){
+            ans.push_back(')');
+            backtrack(o,c+1,n,ans,res);
+            ans.pop_back();
+        }
+    }
+    vector<string> generateParenthesis(int n) {
+        string ans;
+        vector<string> res;
+        backtrack(0,0,n,ans,res);
+        return res;
+    }
+};

Leetcode_Practice_Questions/LC_4.cpp

@@ -0,0 +1,13 @@
+class Solution {
+public:
+    double findMedianSortedArrays(vector<int>& nums1, vector<int>& nums2) {
+        nums1.insert(nums1.end(),nums2.begin(),nums2.end());
+        sort(nums1.begin(),nums1.end());
+        int n=nums1.size();
+        if (nums1.size()%2==0){
+            return (nums1[n/2]+nums1[n/2-1])/2.0;
+        }else{
+            return nums1[n/2];
+        }
+    }
+};

Leetcode_Practice_Questions/LC_9.cpp

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    bool isPalindrome(int x) {
+        long k =0;
+        int num=x;
+        while(num>0){
+            int rem;
+            rem=num%10;
+            k=(k*10)+rem;
+            num=num/10;
+        }
+        if(k==x){
+            return bool(1);
+        }else{
+            return bool(0);
+        }
+    }
+};