Recursion types

Recursion/headRecursion.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+#include <string.h>
+
+using namespace std;
+
+void fun1(int n){
+
+if(n > 0){
+
+    fun1(n-1);
+    cout << n <<endl;
+
+}
+}
+
+int main(){
+  int x;
+  cin >> x;
+  fun1(x);
+  return 0;
+}

Recursion/indirectRecursion.cpp

@@ -0,0 +1,23 @@
+#include <iostream>
+#include <string.h>
+
+using namespace std;
+void fun2(int);
+void fun1(int n){
+if(n > 0){
+    cout << n <<endl;
+    fun2(n-1);
+}
+}
+void fun2(int n){
+  if(n > 1){
+    cout << n <<endl;
+    fun1(n/2);
+  }
+}
+int main(){
+  int x;
+  cin >> x;
+  fun1(x);
+  return 0;
+}

Recursion/knightproblem.cpp

@@ -0,0 +1,59 @@
+#include <iostream>
+
+#include <iomanip>
+
+using namespace std;
+
+const int D =8;
+
+bool canPlace(int board[D][D],int n,int r,int c){
+  return
+      r >= 0 && r <n &&
+      c >=0 && c < n &&
+      board[r][c]==0;
+}
+ bool solveKnight(int board[D][D],int n,int move_no,int curRow,int curCol){
+  if(move_no == n*n){
+    return true;
+  }
+   int row_dir[]= {+2,+1,-1,-2,-2,-1,+1,+2};
+   int col_dir[]= {+1,+2,+2,+1,-1,-2,-2,-1};
+   for(int cur_dir =0;cur_dir<8;cur_dir++){
+     int nextRow = curRow  + row_dir[cur_dir];
+     int nextCol = curCol + col_dir[cur_dir];
+     if(canPlace(board,n,nextRow,nextCol) == true){
+       board[nextRow][nextCol]= move_no + 1;
+      bool isSucess= solveKnight(board,n,move_no+1,nextRow,nextCol);
+      if(isSucess ==true){
+        return true;
+      }else {
+        board[nextRow][nextCol]=0;
+
+      }
+     }
+   }
+   return false;
+ }
+ void printBoard(int board[D][D],int n){
+  for(int i=0;i<n;i++){
+    for(int j=0;j <n;j++){
+      cout << setw(3) << board[i][j] << " ";
+    }
+    cout << endl;
+  }
+}
+
+int main(){
+   int board[D][D] = {0};
+   int n;
+   cin >>n;
+
+   board[0][0]=1;
+bool ans =   solveKnight(board,n,1,0,0);
+if(ans == true ){
+
+  printBoard(board,n);
+}else {
+  cout << "sorry!!!";
+}
+}

Recursion/nestedRecursion.cpp

@@ -0,0 +1,18 @@
+#include <iostream>
+#include <string.h>
+
+using namespace std;
+int fun1(int n){
+if(n > 100){
+  return n-10;
+}else{
+return  fun1(fun1(n+11));
+}}
+int main(){
+  int x;
+  int y;
+  cin >> x;
+y =fun1(x);
+cout << y <<endl;
+  return 0;
+}

Recursion/tailRecursion.cpp

@@ -0,0 +1,17 @@
+#include <iostream>
+#include <string.h>
+
+using namespace std;
+
+void fun1(int n){
+
+if(n > 0){
+  cout << n <<endl;
+  fun1(n-1);
+}}
+int main(){
+  int x;
+  cin >> x;
+  fun1(x);
+  return 0;
+}

Recursion/treeRecursion.cpp

@@ -0,0 +1,17 @@
+#include <iostream>
+#include <string.h>
+
+using namespace std;
+void fun1(int n){
+if(n > 0){
+    cout << n <<endl;
+    fun1(n-1);
+    fun1(n-1);
+}
+}
+int main(){
+  int x;
+  cin >> x;
+  fun1(x);
+  return 0;
+}