**Objective:** Given a Binary tree, Find the size of the tree.

Note : Size of the tree is number of nodes in the tree

**Input:** A Binary Tree.

**Output: **Size of the tree.

**Example** :

**Approach :**

- Very Simple solution
- Start from the root.
- Size = 1 (for the root) + Size Of left Sub-Tree + Size Of right Sub-Tree
- solve the left sub-tree and right sub-tree recursively.

**Code:**

public class SizeofTree { | |

public int getSize(Node root){ | |

if(root==null){ | |

return 0; | |

} | |

return 1 + getSize(root.left) + getSize(root.right); | |

} | |

public static void main(String args[]){ | |

Node root = new Node(5); | |

root.left = new Node(15); | |

root.right = new Node(25); | |

root.left.left = new Node(20); | |

root.left.right = new Node(30); | |

root.right.left = new Node(2); | |

root.right.right = new Node(10); | |

SizeofTree t = new SizeofTree(); | |

System.out.println("Size of the Tree is : " + t.getSize(root)); | |

} | |

} | |

class Node{ | |

int data; | |

Node left; | |

Node right; | |

public Node(int data){ | |

this.data = data; | |

this.left = null; | |

this.right = null; | |

} | |

} |

**Output**:

Size of the Tree is : 7

1+3+3=8, nice try

Both of the images represent wrong size 8 instead of 7

Thanks for pointing it out, Corrected the images

Simple java code to get BST size – https://javadiscover.blogspot.com/2018/07/counting-nodes-in-tree-yes-how-to-get.html