算法才是灵魂：从后往前遍历循环3次，每次维护一个递减栈 def fun(l:list): l = list(map(int, l)) if len(l) < 3: return 0 k = 3 ans = [] while k > 0: res = l[-k:] for i in range(len(l)-len(res)-1,-1,-1): if l[i] <= res[0]: res.insert(0,l[i]) ans.append(res[0]) l = res[1:] k -= 1 return ans[0] * 100 + ans[1] * 10 + ans[2] print(fun("2315628")) #128