[理工] [algo] 99台大資工第6題
題目:http://www.lib.ntu.edu.tw/exam/graduate/99/99405.pdf
自己是認為此題沒例子0.0
想法:因題目要求greedy的解要為minimum的兩倍
但假設宇集合 u={1,2,3,4,5,6}
c={ c1={1,2,3} , c2={1,2,4} , c3={3,5} , c4={3,6}}
這樣greedy就要挑c1,c2,c3,c4 ==>size=4
而minimum為c2,c3,c4 ==>size=3
不為兩倍
希望有大大可以提出兩倍的例子...
認為沒有的原因大概是第一題的6a要maximize 詳細的狀況很難用文字表達0.0...
希望有人可以來個例子...感謝
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