【单选题】
设一棵m叉树中有N1个度数为1的结点,N2个度数为2的结点,……,Nm个度数为m的结点,则该树中共有()个叶子结点。
①
<imgwidth="94"height="57"src="http://wljy.whut.edu.cn:80/uploadfiles/word/sjjg06.files/sjjg063160.png">
②
<imgwidth="52"height="57"src="http://wljy.whut.edu.cn:80/uploadfiles/word/sjjg06.files/sjjg063184.png">
③
<imgwidth="52"height="57"src="http://wljy.whut.edu.cn:80/uploadfiles/word/sjjg06.files/sjjg063208.png">
④
<imgwidth="117"height="57"src="http://wljy.whut.edu.cn:80/uploadfiles/word/sjjg06.files/sjjg063232.png">