diff --git a/Arrays/1D Array/solution.c b/Arrays/1D Array/solution.c
new file mode 100644
index 0000000..7e11772
--- /dev/null
+++ b/Arrays/1D Array/solution.c	
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+int main(){
+	int num,arr[100],i;
+	 scanf("%d",&num);
+	for(i=0;i<num;i++)
+	       scanf("%d",&arr[i]);// Reading input from STDIN
+	for(i=num-1;i>=0;i--)
+	       printf("%d\n",arr[i]);// Writing output to STDOUT
+}
+
diff --git a/Arrays/Multi-D Array/solution.c b/Arrays/Multi-D Array/solution.c
new file mode 100644
index 0000000..d19c824
--- /dev/null
+++ b/Arrays/Multi-D Array/solution.c	
@@ -0,0 +1,34 @@
+/*#include<stdio.h>
+void main()
+{
+int i,r,c,j,arr[10][10];
+scanf("%d %d ",&r,&c);
+for(i=0;i<r;i++)
+   for(j=0;j<c;j++)
+       scanf("%d",&arr[i][j]);
+for(i=0;i<c;i++)
+  { for(j=0;j<r;j++)
+       {printf("%d ",arr[j][i]);
+       }
+    printf("\n");
+  }
+
+}
+*/
+#include<stdio.h>
+int main()
+{
+	int arr[100][100],m,n,i,j;
+	scanf("%d  %d",&m,&n);
+	for(i=0;i<m;i++)
+	{
+		for(j=0;j<n;j++)
+			scanf("%d",&arr[i][j]);
+	}
+	for(i=0;i<n;i++)
+	{
+		for(j=0;j<m;j++)
+			printf("%d ",arr[j][i]);
+		printf("\n");
+	}
+}
diff --git a/Hash Tables/Hash Tables/solution.c b/Hash Tables/Hash Tables/solution.c
new file mode 100644
index 0000000..81e15c8
--- /dev/null
+++ b/Hash Tables/Hash Tables/solution.c	
@@ -0,0 +1,23 @@
+#include<stdio.h>
+ main()
+{
+	int roll,n,i=0,ans[100],j;
+	char name[100],hash[100][100];
+	scanf("%d",&n);
+	while(n>i)
+	{
+		scanf("%d %s%*c",&roll,name);
+		for(j=0;name[j]!='\0';j++)
+			hash[roll][j]=name[j];
+		i++;
+	}
+	scanf("%d",&n);
+	i=0;
+	while(n>i)
+	{
+		scanf("%d",&ans[i]);
+		i++;
+	}
+	for(i=0;i<n;i++)
+	printf("%s\n",hash[ans[i]]);
+}
diff --git a/Queues/Queues/solution.c b/Queues/Queues/solution.c
new file mode 100644
index 0000000..e93a7a0
--- /dev/null
+++ b/Queues/Queues/solution.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+int main()
+{
+int Q[100],front,rear,x,size;
+int N;
+char T;
+front=rear=0;
+scanf("%d",&N);
+while(N--)
+{
+scanf(" %c",&T);
+if(T=='E')
+{
+scanf("%d",&x);
+Q[rear]=x;
+rear++;
+size=rear-front;
+printf("%d\n",size);
+}
+else if(T=='D')
+{
+if(front==rear)
+printf("1 ");
+else
+{
+printf("%d ",Q[front]);
+Q[front]=0;
+front++;}
+size=rear-front;
+printf("%d\n",size);
+
+}
+}
+}
diff --git a/Stacks/Stacks/solution.c b/Stacks/Stacks/solution.c
new file mode 100644
index 0000000..ee6e426
--- /dev/null
+++ b/Stacks/Stacks/solution.c
@@ -0,0 +1,85 @@
+/*lude<stdio.h>
+int top=-1,val,stack[100];
+int ch,n,i;
+void pop()
+{
+top=top-1;
+}
+void push(int stack[],int val)
+{
+top=top+1;
+stack[top]=val;
+}
+void main()
+{
+ scanf("%d",&n);
+ for(i=0;i<n;i++)
+  { 
+    scanf("%d",&ch);
+    if(ch==1)
+     {
+      if(top==0)
+         printf("\nNo food");
+      else
+       {
+        printf("%d\n",stack[top]);
+        pop();
+        }
+     }
+   if(ch==2)
+    {
+     if(top!=99)
+       {
+         scanf("%d",&val);
+         push(stack,val);
+        }
+   }
+  
+  }
+}
+*/
+#include <stdio.h>
+#include <math.h>
+int top=-1;
+void pop()
+{
+top=top-1;
+}
+void push(int stack[],int val)
+{
+top=top+1;
+stack[top]=val;
+}
+int main()
+{
+int n,a,b,val,max;
+scanf("%d",&n);
+max=n;
+int stack[n];
+for(int i=0;i<n;i++)
+{
+scanf("%d",&a);
+if(a==1)
+{
+if(top==-1)
+{
+printf("No food\n");
+}
+else
+{
+printf("%d\n",stack[top]);
+pop();
+}
+}
+else
+{
+if(top!=max-1)
+{
+scanf("%d",&val);
+push(stack,val);
+}
+}
+
+}
+return 0;
+}
diff --git a/Trees/Binary Search Tree/solution.c b/Trees/Binary Search Tree/solution.c
new file mode 100644
index 0000000..6c1210f
--- /dev/null
+++ b/Trees/Binary Search Tree/solution.c	
@@ -0,0 +1,67 @@
+#include<stdio.h>
+#include<malloc.h>
+struct node
+{
+int data;
+struct node* lchild;
+struct node* rchild;
+};
+struct node* root;
+struct node* insert(struct node* root,int it)
+{
+  if(root==NULL)
+    {
+      root=(struct node *)malloc(sizeof(struct node));
+        root->lchild=NULL;
+        root->rchild= NULL;
+        root->data = it;
+        return root;
+    }
+   else
+    {
+        if(it< root->data )
+            root->lchild=insert(root->lchild,it);
+        else if(it>root->data)
+            root->rchild=insert(root->rchild,it);
+        else
+            printf(" Duplicate Element !! Not Allowed !!!");
+        return(root);
+    }
+}
+void create(int n)
+{int i,it;
+ for(i=0;i<n;i++)
+   {  
+      scanf("%d",&it);
+      root=insert(root,it);
+   }
+}
+void preorder(struct node *root)
+{
+   if(root!=NULL)
+    {  
+       printf("%d\n",root->data);
+       preorder(root->lchild);
+       preorder(root->rchild);
+    }
+}
+void find(int m,struct node *root)
+{  if(root->data==m)
+      preorder(root);
+    else if(root->data<m)
+       find(m,root->rchild);
+    else
+        find(m,root->lchild);
+}
+    
+
+main()
+{   int m,n;
+    scanf("%d",&n);
+    create(n);
+    scanf("%d",&m);
+    find(m,root);    
+}
+
+
+
diff --git a/Trees/Binary Tree/solution.c b/Trees/Binary Tree/solution.c
new file mode 100644
index 0000000..b9abc83
--- /dev/null
+++ b/Trees/Binary Tree/solution.c	
@@ -0,0 +1,77 @@
+#include<stdio.h>
+#include<malloc.h>
+struct node
+{
+int data;
+struct node* lchild;
+struct node* rchild;
+}*ptr;
+struct node* root;
+struct node* getnode(int val){
+struct node* temp=(struct node*)malloc(sizeof(struct node));
+temp->data=val;
+temp->lchild=NULL;
+temp->rchild=NULL;
+return temp;
+}
+int getMax(int a, int b){
+    if(a >= b)
+        return a;
+    else
+        return b;
+}
+
+int getHeight(struct node *root){
+    int leftHeight, rightHeight;
+    if(root == NULL)
+        return 0;
+    leftHeight = getHeight(root->lchild);
+    rightHeight = getHeight(root->rchild);
+     
+    return getMax(leftHeight, rightHeight) + 1;
+}
+ 
+
+int getDiameter(struct node *nodePtr) {
+   /* Empty Tree  */
+   if (nodePtr == NULL)
+     return 0;
+ 
+ 
+  int leftHeight = getHeight(nodePtr->lchild);
+  int rightHeight = getHeight(nodePtr->rchild);
+ 
+  int leftDiameter = getDiameter(nodePtr->lchild);
+  int rightDiameter = getDiameter(nodePtr->rchild);
+  return getMax(leftHeight + rightHeight + 1, 
+              getMax(leftDiameter, rightDiameter));
+}
+ 
+main()
+{int i,n,m;
+ char s[20];
+ scanf("%d %d",&n,&m);
+ root=getnode(m);
+ for(i=1;i<n;i++)
+ {
+   scanf("%s %d",&s,&m);
+   int j=0;
+   ptr=root;
+   while(s[j]!='\0')
+    {
+      if(s[j]=='L'){
+        if(ptr->lchild==NULL)
+           ptr->lchild=getnode(m);
+        ptr=ptr->lchild;}
+        else
+         {
+         if(ptr->rchild==NULL)
+           ptr->rchild=getnode(m);
+         ptr=ptr->rchild;
+         }
+     j++;
+    }
+ 
+ }
+ printf("%d\n",getDiameter(root));
+}
diff --git a/Trees/Heap/solution.c b/Trees/Heap/solution.c
new file mode 100644
index 0000000..3ae12a0
--- /dev/null
+++ b/Trees/Heap/solution.c
@@ -0,0 +1,29 @@
+#include<stdio.h>
+main()
+{
+    int N,A[100],i,type,q,a,b,j;
+    scanf("%d",&N);
+    for(i=0;i<N;i++)
+         scanf("%d",&A[i]);
+     scanf("%d",&q);
+     while(q>0)
+     {
+         scanf("%d",&a);
+         if(a==1)
+            {   scanf("%d",&b);
+                for(j=0;j<N;j++);
+                    A[j]=b;
+                    N++;
+            }
+        if(a==2)
+          {     int large=A[0];
+                for(j=1;j<N;j++)
+                   {
+                       if(A[j]>large)
+                          large=A[j];
+                   }
+                 printf("%d\n",large);
+          }
+        q--;
+     }
+}
diff --git a/checker.sh b/checker.sh
new file mode 100644
index 0000000..e4a2a70
--- /dev/null
+++ b/checker.sh
@@ -0,0 +1,66 @@
+#!/bin/sh
+# Copyright 2018, Training Cell MEC
+
+CC=cc
+VERSION="0.1"
+
+PROJ_PATH=$(pwd)
+SOL_FILE="solution.c"
+TESTCASE_DIR="tests"
+OUTPUT_DIR=output
+
+HELP_TEXT="Usage: $0 [-c CC ] [-d PATH] [-h] PROBLEM"
+
+PROBLEM=
+
+help() {
+	echo "$HELP_TEXT"
+	exit 0
+}
+
+error_exit() {
+	echo "critical error: $1"
+	exit 1
+}
+
+while [ $# != 0 ]; do
+	case $1 in
+		-h) help ;;
+		-c) CC=$2 ; shift ;;
+		-d) PROJ_PATH=$2 ; shift ;;
+		-*) ;;
+		*) PROBLEM=$1 ;;
+	esac
+	shift
+done
+
+[ -z "$PROBLEM" ] && error_exit "no problem specified"
+
+# scratch directory
+if [ ! -d "${PROJ_PATH}/${OUTPUT_DIR}" ]; then
+	mkdir "${PROJ_PATH}/${OUTPUT_DIR}" ||
+		error_exit "directory creation failed"
+fi
+find "${PROJ_PATH}/${OUTPUT_DIR}/" -maxdepth 1 -type f -delete ||
+	error_exit "directory operation failed"
+
+# build the source
+$CC -o "${PROJ_PATH}/${OUTPUT_DIR}/bin" "${PROJ_PATH}/${PROBLEM}/${SOL_FILE}" ||
+	error_exit "compilation failed"
+
+# verify the output
+for cs in $(find "${PROJ_PATH}/${PROBLEM}/${TESTCASE_DIR}/"\
+	-maxdepth 1 -iname 'in*.txt' -type f -printf '%f '); do
+	op_n=$(echo $cs | sed 's/in\(.\)\.txt/\1/') # n as in nth test case
+
+	"${PROJ_PATH}/${OUTPUT_DIR}/bin" <"${PROJ_PATH}/${PROBLEM}/${TESTCASE_DIR}/in${op_n}.txt"\
+		>"${PROJ_PATH}/${OUTPUT_DIR}/op${op_n}.txt"
+
+	cat "${PROJ_PATH}/${OUTPUT_DIR}/op${op_n}.txt" | sha1sum | cut -d ' ' -f 1 |
+		cmp -s -n 40 "${PROJ_PATH}/${PROBLEM}/${TESTCASE_DIR}/op${op_n}_hashed.txt" - &&
+		echo "test case ${op_n} passed" || echo "test case ${op_n} failed"
+done
+
+# cleanup
+rm -r "${PROJ_PATH}/${OUTPUT_DIR}/" ||
+       error_exit "directory operation failed"