code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007

struct Node
{
int data;
struct Node *left;
struct Node *right;
int height;
};

Node *newnode(int key)
    {
    Node *temp=new Node;
    temp->data=key;
    temp->left=NULL;
    temp->right=NULL;
    temp->height=1;
    return temp;
    }

int height(Node *root)//return height of Node
    {
    if(root==NULL)  return 0;;
    return root->height;
    }
Node *left_rotate(Node *root)
    {
    Node *x=root->right;
    Node *y=x->left;
    x->left=root;
    root->right=y;
    root->height=1+max(height(root->left),height(root->right));
    x->height=1+max(height(x->left),height(x->right));
    return x;
    }

Node *right_rotate(Node *root)
    {
    Node *x=root->left;
    Node *y=x->right;
    x->right=root;
    root->left=y;
    root->height=1+max(height(root->left),height(root->right));
    x->height=1+max(height(x->left),height(x->right));
    }

Node* insertToAVL( Node* root, int key)
{
if(root==NULL)  return newnode(key);
if(root->data==key) return root;
else if(root->data >key) root->left=insertToAVL(root->left,key);
else root->right=insertToAVL(root->right,key);

root->height=1+max(height(root->left),height(root->right));
int balance=height(root->left)-height(root->right);

if(balance>1 && root->left->data >key )//LL case
    {
    return right_rotate(root);
    }
 if(balance > 1 && root->left-> data <key)//LR case
    {
    root->left=left_rotate(root->left);
    return right_rotate(root);
    }
 if(balance <-1 && root->right ->data <key) //RR case
    {
    return left_rotate(root);
    }
 if(balance<-1 && root->right ->data> key)//RL case
    {
    root->right=right_rotate(root->right);
    return left_rotate(root);
    }
return root;
}
void print(Node *root)//Inorder traversal of nodes.
{
if(root==NULL) return;
cout<<root->data<<" ";
print(root->left);
print(root->right);
}
int find_min(Node *root,int key)//Find the minimum of A subtree
{
while(root->left!=NULL) root=root->left;
int temp=root->data;
root->data=key;
return temp;
}
int getfactor(Node *root){
return (height(root->left)-height(root->right));
}
Node *delete_node(Node *root,int &key)//Delete a key from the BST !.
{
if(root==NULL) return NULL;
if(root->data==key)
{
if(root->left==NULL && root->right==NULL)
return NULL;
else if(root->left==NULL && root->right!=NULL)
{
Node *temp=root->right;
return temp;
}
else if(root->left!=NULL && root->right==NULL)
{
Node *temp=root->left;
return temp;
}
else
{
int Min=find_min(root->right,key);
root->data=Min;
root->right=delete_node(root->right,key);
return root;
}
//root->height=1+root->height;
delete root;
}
else if(root->data > key) root->left=delete_node(root->left,key);
else root->right=delete_node(root->right,key);
root->height=1+max(height(root->left),height(root->right));
int balance=height(root->left)-height(root->right);
if(balance <-1 && getfactor(root->right)<0)
{
root=left_rotate(root);
}
if(balance <-1 && getfactor(root->right)>=0)
{
root->right=right_rotate(root->right);
root=left_rotate(root);
}
if(balance >1 && getfactor(root->left)>=0)
{
root=right_rotate(root);
}
if(balance >1 && getfactor(root->left)<0)
{
root->left=left_rotate(root->left);
root=right_rotate(root);
}

return root;
}
int main() {
//std::ios::sync_with_stdio(false);
Node *head=NULL;
int n,key;
do
{
sc(n);
switch(n)
{
case 1 :
sc(key);
head=insertToAVL(head,key);//Insertion in binary tree
break;
case 2 ://Print the elements of binary tree in inorder format
print(head);
pfnl();
break;
case 3://Deltetion of elements from binary tree
cin>>key;
head=delete_node(head,key);
}
}while(n!=4); //Press 4 to exit the loop
return 0;
}

problem id:--http://practice.geeksforgeeks.org/problems/four-elements/0

code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007

int binary_loc(int arr[],int n,int sum){
int mid,l=0,r=n-1;
while(l<=r){
mid=(l+r)/2;
if(arr[mid]<sum) l=mid+1;
else r=mid-1;
}
return mid;

}

bool find_sum(int arr[],int n,int sum){
    unordered_set<int> mymap;
rep(i,n-3){
rep2(j,i+1,n-1){
   mymap.clear();
rep2(k,j+1,n){
int temp=arr[i]+arr[j]+arr[k];
if(mymap.find(-temp)!=mymap.end()) return 1;
mymap.insert(arr[k]-sum);
}
}
}

return 0;
}

int main(int argc, char **argv) {
//std::ios::sync_with_stdio(false);
int arr[105];
int t;
sc(t);
while(t--)
{
int n,sum;
sc(n);
rep(i,n) sc(arr[i]);
sc(sum);
sort(arr,arr+n);//sorting is better than comparing in O(n^3)
//debug(binary_loc(arr,n,sum));
//we'll use binary_loc to find the upper bound upto which we have check in arrya
//that means binary_loc returns the index of an array such that
//arr[binary_loc()] val is greater than sum or equal to sum
// and we don't want to compare beyond sum value in array
bool ans=find_sum(arr,binary_loc(arr,n,sum)+1,sum);
cout<<ans;
pfnl();
}
return 0;
}

problem id:--http://practice.geeksforgeeks.org/problems/longest-palindromic-subsequence/0

code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
//#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007
int dp[1005][1005];

int palind_substr(string str)
{
int n=str.length();
rep(i,n) rep(j,n) dp[i][j]=0;
rep(i,n) dp[i][i]=1;
int l=1;
while(l<n)
{
int i=0;
while(i<n-l)
{
if(str[i]==str[i+l]) {dp[i][i+l]=2; if(l>1) dp[i][i+l]+=dp[i+1][i+l-1];}
else dp[i][i+l]=max(dp[i][i+l-1],dp[i+1][i+l]);
++i;
}
++l;
}
//rep(i,n) {rep(j,n) pf(dp[i][j]); cout<<'\n'; }
return dp[0][n-1];
}

int main(int argc, char **argv) {
//std::ios::sync_with_stdio(false);
int t;
sc(t);
while(t--)
{
string str;
cin>>str;
int ans=palind_substr(str);
cout<<ans<<'\n';
}
return 0;
}

problem id:--http://practice.geeksforgeeks.org/problems/minimum-sum-of-two-elements-from-two-arrays/0

code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007

int main(int argc, char **argv) {
//std::ios::sync_with_stdio(false);
priority_queue<pair<int,int> > a,b;
int t;
sc(t);
while(t--)
{
int n,num;
sc(n);
a=priority_queue<pair<int,int> > ();
b=priority_queue<pair<int,int> > ();
rep(i,n) {sc(num); a.push(mp(-num,i));}
rep(i,n) {sc(num); b.push(mp(-num,i));}
int ans=0;
int num1=-a.top().X ,num2=-b.top().X;
if(a.top().Y !=b.top().Y)
   ans=num1+num2;
else
   {
   a.pop(); b.pop();
   ans=min(num1 - b.top().X , num2 - a.top().X);
   }
cout<<ans<<'\n';
}
return 0;
}

problem id::--http://practice.geeksforgeeks.org/problems/reverse-a-string-with-spaces-intact/0

code:--

#include <bits/stdc++.h>

using namespace std;
#define ll   long long
#define      pii               std::pair<int,int>
#define      vi                std::vector<int>
#define      vll               std::vector<long long>
#define      mp(a,b)           make_pair(a,b)
#define      pb(a)             push_back(a)
#define sc(x)   scanf("%d",&x)
#define scll(x)   scanf("%lld",&x)
#define sc2(x,y)   scanf("%d%d",&x,&y)
#define sc3(x,y,z)   scanf("%d%d%d",&x,&y,&z)
#define     pf(x)   printf("%d ",x)
#define     pf2(x,y)   printf("%d %d ",x,y)
#define     pf3(x,y,z)   printf("%d %d %d ",x,y,z)
#define pfnl()   putchar('\n');
#define      each(it,s)        for(auto it = s.begin(); it != s.end(); ++it)
#define      rep(i, n)         for(int i = 0; i < (n); ++i)
#define rep2(i,j,n)   for(int i = j; i < (n); ++i)
#define      fill(a)           memset(a, 0, sizeof (a))
#define      sortA(v)          sort(v.begin(), v.end())
#define      sortD(v)          sort(v.begin(), v.end(), greater<auto>())
#define      X                 first
#define      Y                 second

#define debug(x) cerr<<"debug->"<<#x<<"::"<<x<<endl
#define debug2(x,y) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n"
#define debug3(x,y,z) cerr<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n"
#define MOD 1000000007

int main(int argc, char **argv) {
//std::ios::sync_with_stdio(false);
int t;
sc(t);
cin.ignore(1,'\n');
string str,ans;
while(t--)
{
getline(cin,str);
ans="";
int i=str.length()-1,j=0;
while(i>=0)
{
if(str[i]==' ') { --i; continue; }
if(str[j]==' ') { ans+=str[j]; ++j;  continue;}
ans+=str[i];
++j,--i;
}
cout<<ans;
pfnl();
}
return 0;
}