Property 3: to any binary tree T, if number of leaves is no. the number of node (degree of node is 2)is n2, then n0=n2 +1. Prove: if the number of node(degree of node is 1)is nl, the total number of node is n, the total number of edge is e, then as the definition of binary tree, n=n0+n1+n2 e=2n2+nl=n-1 SO, there comes 2n2+nl=n0+nl+n2 n2=n0-1n0=n2+1Property 3: to any binary tree T, if number of leaves is n0, the number of node (degree of node is 2) is n2, then n0= n2 +1. Prove: if the number of node (degree of node is 1) is n1, the total number of node is n, the total number of edge is e, then as the definition of binary tree, n = n0 + n1 + n2 e = 2n2 + n1 = n – 1 so，there comes 2n2 + n1 = n0 + n1 + n2 - 1 n2 = n0 - 1 n0 = n2 + 1