AlvinYoung：我第一题30%，第二题80%，两道题一直报错数组越界，就很困惑

胜利201909282147405：第四题：dp，递归深度太大。 if __name__ == '__main__': k = input() k = int(k) S = 'S' A = 'A' B = 'B' C = 'C' d = [0] def Foot(s, k): if k == 0: if s == S: d[0] += 1 return 0 k -= 1 if s == S: Foot(A, k) Foot(B, k) Foot(C, k) return if s == A: Foot(S, k) Foot(B, k) Foot(C, k) return if s == B: Foot(S, k) Foot(A, k) Foot(C, k) return if s == C: Foot(S, k) Foot(A, k) Foot(B, k) return Foot(S, k)

yoyozy：第二题AC代码，相当于计算最少有几个递增序列。 nums=[[4,1],[9,3],[5,5],[2,4],[2,1]] def solution(nums): nums.sort(key=lambda x:(x[0],x[1])) res=[nums[0]] for num in nums[1:]: found=False for i in range(len(res)): if num[0]>=res[i][0] and num[1]>=res[i][1]: res[i]=num found=True break if found==False: res.append(num) return len(res) solution(nums)