diff --git a/Backtracking/sudoku_solve.cpp b/Backtracking/sudoku_solve.cpp
new file mode 100644
index 000000000..e1e008a91
--- /dev/null
+++ b/Backtracking/sudoku_solve.cpp
@@ -0,0 +1,102 @@
+#include<iostream>
+using namespace std;
+///N=9;
+int n=9;
+
+
+bool isPossible(int mat[][9],int i,int j,int no){
+    ///Row or col nahin hona chahiye
+    for(int x=0;x<n;x++){
+        if(mat[x][j]==no||mat[i][x]==no){
+            return false;
+        }
+    }
+
+    /// Subgrid mein nahi hona chahiye
+    int sx = (i/3)*3;
+    int sy = (j/3)*3;
+
+    for(int x=sx;x<sx+3;x++){
+        for(int y=sy;y<sy+3;y++){
+            if(mat[x][y]==no){
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+void printMat(int mat[][9]){
+
+    for(int i=0;i<n;i++){
+        for(int j=0;j<n;j++){
+            cout<<mat[i][j]<<" ";
+            if((j+1)%3==0){
+                cout<<'\t';
+            }
+
+        }
+         if((i+1)%3==0){
+                cout<<endl;
+        }
+            cout<<endl;
+    }
+}
+
+
+bool solveSudoku(int mat[][9],int i,int j){
+    ///Base Case
+    if(i==9){
+        ///Solve kr chuke hain for 9 rows already
+        printMat(mat);
+        return true;
+    }
+
+    ///Crossed the last  Cell in the row
+    if(j==9){
+        return solveSudoku(mat,i+1,0);
+    }
+
+    ///Blue Cell - Skip
+    if(mat[i][j]!=0){
+        return solveSudoku(mat,i,j+1);
+    }
+    ///White Cell
+    ///Try to place every possible no
+    for(int no=1;no<=9;no++){
+        if(isPossible(mat,i,j,no)){
+            ///Place the no - assuming solution aa jayega
+            mat[i][j] = no;
+            bool aageKiSolveHui = solveSudoku(mat,i,j+1);
+            if(aageKiSolveHui){
+                return true;
+            }
+            ///Nahin solve hui
+            ///loop will place the next no.
+        }
+    }
+    ///Sare no try kr liey, kisi se bhi solve nahi hui
+    mat[i][j] = 0;
+    return false;
+}
+
+int main(){
+
+int mat[9][9] =
+        {{5,3,0,0,7,0,0,0,0},
+        {6,0,0,1,9,5,0,0,0},
+        {0,9,8,0,0,0,0,6,0},
+        {8,0,0,0,6,0,0,0,3},
+        {4,0,0,8,0,3,0,0,1},
+        {7,0,0,0,2,0,0,0,6},
+        {0,6,0,0,0,0,2,8,0},
+        {0,0,0,4,1,9,0,0,5},
+        {0,0,0,0,8,0,0,7,9}};
+
+printMat(mat);
+cout<<"Solution "<<endl;
+solveSudoku(mat,0,0);
+
+
+return 0;
+}
diff --git a/sleep sort.c b/sleep sort.c
new file mode 100644
index 000000000..e0217ca25
--- /dev/null
+++ b/sleep sort.c	
@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <windows.h>
+#include <process.h>
+ 
+void routine(void *a)
+{
+    int n = *(int *) a; // typecasting from void to int
+ 
+    // Sleeping time is proportional to the number
+    // More precisely this thread sleep for 'n' milliseconds
+    Sleep(n);
+ 
+    // After the sleep, print the number
+    printf("%d ", n);
+
+void sleepSort(int arr[], int n)
+{
+    // An array of threads, one for each of the elements
+    // in the input array
+    HANDLE threads[n];
+ 
+    // Create the threads for each of the input array elements
+    for (int i = 0; i < n; i++)
+        threads[i] = (HANDLE)_beginthread(&routine, 0,  &arr[i]);
+ 
+    // Process these threads
+    WaitForMultipleObjects(n, threads, TRUE, INFINITE);
+    return;
+}
+ 
+// Driver program to test above functions
+int main()
+{
+    // Doesn't work for negative numbers
+    int arr[] = {34, 23, 122, 9};
+    int n = sizeof(arr) / sizeof(arr[0]);
+ 
+    sleepSort (arr, n);
+ 
+    return(0);
+}
\ No newline at end of file
diff --git a/spiral_print.cpp b/spiral_print.cpp
new file mode 100644
index 000000000..03ea074e9
--- /dev/null
+++ b/spiral_print.cpp
@@ -0,0 +1,68 @@
+#include<iostream>
+using namespace std;
+
+void genArray(int a[][10],int r,int c){
+
+    int value=1;
+    for(int i=0;i<r;i++){
+        for(int j=0;j<c;j++){
+            a[i][j] = value;
+            cout<<a[i][j]<<" ";
+            value++;
+        }
+        cout<<endl;
+    }
+}
+void spiralPrint(int a[][10],int r,int c){
+
+    int startRow=0,endRow=r-1;
+    int startCol =0, endCol = c-1;
+    int cnt=0;
+
+    while(startRow<=endRow && startCol<=endCol){
+
+        ///Print start row
+        for(int i=startCol;i<=endCol;i++,cnt++){
+            cout<<a[startRow][i]<<" ";
+        }
+        startRow++;
+
+        ///Print the end col
+        for(int i=startRow;i<=endRow;i++,cnt++){
+            cout<<a[i][endCol]<<" ";
+        }
+        endCol--;
+
+        ///Print the end row
+        if(cnt==r*c){
+            break;
+        }
+
+        for(int i=endCol;i>=startCol;i--,cnt++){
+            cout<<a[endRow][i]<<" ";
+        }
+        endRow--;
+
+        ///Print the start Col
+        if(cnt==r*c){
+            break;
+        }
+        for(int i=endRow;i>=startRow;i--,cnt++){
+            cout<<a[i][startCol]<<" ";
+        }
+        startCol++;
+    }
+}
+
+int main()
+{
+    int a[10][10];
+
+    int r,c;
+    cin>>r>>c;
+    genArray(a,r,c);
+    spiralPrint(a,r,c);
+
+
+return 0;
+}