二叉树之统计二叉树中叶子节点的个数

二叉树之统计二叉树中叶子节点的个数

二叉树的叶子节点是既没有左子树又没有右子树的特殊的节点，使用递归我们可以方便的计算出共有多少叶子节点。

public class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

    TreeNode() {
    }
    TreeNode(int val) {
        this.val = val;
    }
    TreeNode(int val, TreeNode left, TreeNode right) {
        this.val = val;
        this.left = left;
        this.right = right;
    }
}

public class NumberOfLeafs {
    public static void main(String[] args) {
        TreeNode treeNode = new TreeNode();
        numberOfLeafs(treeNode);
    }

    private static Integer numberOfLeafs(TreeNode treeNode) {
        int nodes=0;
        if(treeNode==null){
            return 0;
        }
        if(treeNode.left==null&&treeNode.right==null) {
            return 1;
        }else {
            nodes+=numberOfLeafs(treeNode.left)+numberOfLeafs(treeNode.right);
        }
        return nodes;
    }
}

    static Integer nums=0;
    private static void numberOfLeafs1(TreeNode treeNode) {
        if(treeNode==null){
            return;
        }
        if(treeNode.left==null&&treeNode.right==null){
            nums++;
        }
        numberOfLeafs1(treeNode.left);
        numberOfLeafs1(treeNode.right);
    }