推 nana0130:啊 ！謝謝你 03/25 00:41
※ 引述《nana0130 (小那)》之銘言：
: If a planar connected graph G has 5 region of degree 4,
: 11 region of degree 5, 2 regions of degree 7,
: 2 regionsof degree 8, and 1 region of degree 9, then G has ______
: edges and ______ vertices.
一個邊可以決定兩個region
=> 5*4 + 11*5 + 2*7 + 2*8 + 1*9 = 114 = 2*(edge數)
=> edge數 = 57 ###
=> Eular's plan Theorem V-E+R=2
=> V-E+R = V - 57 + (5+11+2+2+1)
=> vertices數 = 38 ###
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