一開始想用DP 幹發現怎麼都D不太出來:( 後來發現好像不管先碰ab或先碰ba，最後總共碰的次數都會一樣 (不會因為某個地方選擇碰ba不碰ab，造成後面總共碰的對數少了幾對) 總而言之就變成說 若y>x，就先全碰ba，最後再來處理ab 反之就先全碰ab，最後再來處理ba 大概是這樣 寫得醜醜:( def maximumGain(self, s: str, x: int, y: int) -> int: stk = [] score = 0 for c in s: if x >= y: if stk and stk[-1] == 'a' and c == 'b': stk.pop() score += x else: stk.append(c) else: if stk and stk[-1] == 'b' and c == 'a': stk.pop() score += y else: stk.append(c) stk2 = [] for c in stk: if stk2 and stk2[-1] == 'a' and c == 'b': stk2.pop() score += x elif stk2 and stk2[-1] == 'b' and c == 'a': stk2.pop() score += y else: stk2.append(c) return score -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 125.228.146.144 (臺灣) ※ 文章網址: https://www.ptt.cc/bbs/Marginalman/M.1720798384.A.EB7.html