【python】习题 1-5周（中）https://developer.aliyun.com/article/1507462?spm=a2c6h.13148508.setting.24.1b484f0eD2AqhJ
7-3 求e的值
n = float(input()) i = 1 e = 0.0 jc = 1.0 while jc > n: e = e + jc j = 1 for k in range(1, i + 1): j = j * k jc = 1.0 / j i += 1 print("e={:.6f}".format(e))
7-4 斐波那契数
用常规做法，最后一个测试点会超时。
更高效的做法是：找出输出结果的规律，根据输入的n的值直接构造输出结果。列举如下：
n=7，结果是: no no yes no no no yes
n=11,结果是: no no yes no no no yes no no no yes
n=15,结果是: no no yes no no no yes no no no yes no no no yes
n=19的话，结果是多少？
# 6分答案 num = int(input()) flag = 0 for i in range(num): if i < 2: print("no ", end="") elif i >= 2: if i % 4 == 2: print("yes ", end="") else: print("no ", end="") # 6分答案 ------时间超时 num = int(input()) for i in range(num): if i == 2 or (i - 2) % 4 == 0: print('yes', end=' ') else: print('no', end=' ')
用了for循环 时间复杂度O(n)还是会时间超时
#满分答案 Fibonacci = "yes no no no " num = int(input()) if num == 1: print("no ", end="") if num <= 2: print("no no ", end="") elif num > 2: a = (num - 2) print("no no ", end="") x = a // 4 if a % 4 == 0: print(Fibonacci*x) if a % 4 == 1: if x == 0: print(Fibonacci[0:4]) else: print(Fibonacci*x+Fibonacci[0:4]) if a % 4 == 2: if x == 0: print(Fibonacci[0:7]) else: print(Fibonacci * x+Fibonacci[0:7]) if a % 4 == 3: if x == 0: print(Fibonacci[0:10]) else: print(Fibonacci * x+Fibonacci[0:10]) # num = int(input()) # if num == 1: # print("no ", end="") # if num <= 2: # print("no no ", end="") # elif num > 2: # a = (num - 2) # print("no no ", end="") # x = a // 4 # if a % 4 == 0: # print("yes no no no " * x, end="") # if a % 4 == 1: # if x == 0: # print("yes ", end="") # else: # print("yes no no no " * x, end="") # print("yes ", end="") # if a % 4 == 2: # if x == 0: # print("yes no ", end="") # else: # print("yes no no no " * x, end="") # print("yes no ", end="") # if a % 4 == 3: # if x == 0: # print("yes no no ", end="") # else: # print("yes no no no " * x, end="") # print("yes no no ", end="") # 方法2 n=input() n=int(n) a='no no yes no no no yes no ' b=[1,2,0,2,2,1,0,1] x=n//8 def f(m): for i in range(m): if (b[i % 8]) == 0: print("yes ", end="") else: print("no ", end="") if x<0: f(x) else: print(a*x,end='') f(n%8)
7-5 求简单交错序列前N项和
n = int(input()) ans = 0 flag = 1 num = 1 for i in range(1, n + 1): ans += flag * 1.0 / num num += 3 flag = -flag print("sum = {:.3f}".format(ans))
7-6 求整数序列中出现次数最多的数
a = input().split() #在一行中输入多个数 i = int(a[0]) + 1 #确定第一个数字大小即是列表应有的长度 del a[i:] #删除多余输入的数字 del a[0] #删除第一个数字 #现在a中存储的即为要求序列 num = 0 MaxCount = 0 for i in a: #从第一个数字开始遍历（第一个循环） count = 0 for j in a: #从第一个数字开始遍历（第二个循环） if j == i: #如果两个数字相等，那么这个数字的数量加一 count += 1 if MaxCount < count: #判断数量最多的数字并存储 MaxCount = count num = i print("{} {}".format(num,MaxCount)) # print(num, end = ' ') # print(MaxCount)
7-7 求符合给定条件的整数集
a = int(input()) n = 0 b = a + 4 for i in range(a, b): for j in range(a, b): if i == j: continue for k in range(a, b): if k == i or k == j: continue n += 1 # 换行 if n < 6: print(i * 100 + j * 10 + k, end=" ") else: n = 0 print(i * 100 + j * 10 + k)
也可以使用暴力解法 一共6种情况，直接输出
a = int(input()) if a==1: print("""123 124 132 134 142 143 213 214 231 234 241 243 312 314 321 324 341 342 412 413 421 423 431 432""") elif a==2: print("""234 235 243 245 253 254 324 325 342 345 352 354 423 425 432 435 452 453 523 524 532 534 542 543""") elif a==3: print("""345 346 354 356 364 365 435 436 453 456 463 465 534 536 543 546 563 564 634 635 643 645 653 654""") elif a==4: print("""456 457 465 467 475 476 546 547 564 567 574 576 645 647 654 657 674 675 745 746 754 756 764 765""") elif a==5: print("""567 568 576 578 586 587 657 658 675 678 685 687 756 758 765 768 785 786 856 857 865 867 875 876 """) elif a==6: print("""678 679 687 689 697 698 768 769 786 789 796 798 867 869 876 879 896 897 967 968 976 978 986 987""")
7-8 画菱形
n = int(input()) for i in range(1, n + 1): for j in range(1, n - i + 1): print(" ", end="") for j in range(1, 2 * i - 1 + 1): print("*", end="") print("\n", end="") for i in range(1, n - 1 + 1): for j in range(1, i + 1): print(" ", end="") for j in range(1, 2 * n - 1 - 2 * i + 1): print("*", end="") print("\n", end="")
7-9 求集合数据的均方差
import math n = int(input()) arr = input() num = [int(n) for n in arr.split()] sum = 0 avg = 0.0 x = 0.0 # for i in num: # print(i) for i in range(0, len(num)): # print(num[i]) sum += num[i] avg = sum * 1.0 / n for i in range(0, len(num)): x += (num[i] - avg) * (num[i] - avg) result = math.sqrt(x / n) print("{:.5f}".format(result))
7-10 组合数的和
不知道为什么 但是是错误的
# 0 a = [int(i) for i in input().split()] n = a[0] result = 0 for i in range(1, n + 1): for j in range(1, n + 1): if j==i: continue else: result += a[i] * 10 +a[j] print(result) # 0 a = input().split() sum = 0 sum2 = 0 for i in range(1, len(a)): sum += int(a[i]) for i in range(1, len(a)): sum2 += int(a[i]) * 10 * (len(a) - 2) + sum - int(a[i]) print(sum2)
终于答对了
# 10 import sys num = list(map(int, sys.stdin.read().split())) print(sum(num[1:] * (num[0] - 1) * 11))
第10题，输入有两行。输入样例改为：
3
2 5 8
# 10 n = int(input()) a = [int(i) for i in input().split()] result = 0 for i in range(0, n ): for j in range(0, n ): if j==i: continue else: result += a[i] * 10 +a[j] print(result)
7-11 输出素数之和
# 方法1 def isprime(n): if n <= 1: return False for i in range(2, n): if n % i == 0: return False return True def f(n): count = 0 s = 0 while count < 10 and n > 1: if isprime(n): count += 1 print(n, end=" ") s += n n -= 1 print() return s num = int(input()) print("sum = {}".format(f(num))) # 方法2 import heapq n = int(input()) sums = 0 nums = [] for i in range(2, n): for j in range(2, i): if i % j == 0: break else: sums += i nums.append(int(i)) maxnums = heapq.nlargest(10, nums) total = sum(maxnums) for i in maxnums: print(i, end=' ') print() print("sum = {:.0f}".format(total))
7-12 暴力小学(二年级篇)-求出2个三位数
count = 0 t = 0 n = int(input()) aa = {} bb = {} for a1 in range(1, 7): for a2 in range(1, 7): for a3 in range(1, 7): for b1 in range(1, 7): for b2 in range(1, 7): for b3 in range(1, 7): if ((a1 * 100 + a2 * 10 + a3 - b1 * 100 - b2 * 10 - b3 == n) and a1 != a2 and a1 != a3 and a1 != b1 and a1 != b2 and a1 != b3 and a2 != a3 and a2 != b1 and a2 != b2 and a2 != b3 and a3 != b1 and a3 != b2 and a3 != b3 and b1 != b2 and b1 != b3 and b2 != b3): aa[count] = a1 * 100 + a2 * 10 + a3 bb[count] = b1 * 100 + b2 * 10 + b3 count += 1 print(count) for i in range(0, count): print("{}-{}".format(aa[i], bb[i]))
7-13 高空坠球
# 9 dis = [] # 距离 height = [] # 高度 h, time = map(int, input().split()) for i in range(1, time + 1): if i == 1: dis.append(h) else: dis.append(2 * h) h /= 2 height.append(h) print("{:.1f} {:.1f}".format(sum(dis), height[-1]))
这里9分是因为：非零返回了
# 10 height, n = map(int, input().split()) sum = 0 h = 0 for i in range(0, n + 1): if i == 0: sum = 0 h = 0 if i == 1: sum = height h = height / 2.0 if i > 1: sum = sum + h * 2 h = h / 2 print("{:.1f} {:.1f}".format(sum, h))
7-14 二分法求多项式单根
# 方法1 import math a = list(float(x) for x in input().split()) b = list(float(x) for x in input().split()) while True: if b[1] - b[0] <= 0.01: break f1 = a[0] * pow(b[0], 3) + a[1] * pow(b[0], 2) + a[2] * b[0] + a[3] f2 = a[0] * pow(b[1], 3) + a[1] * pow(b[1], 2) + a[2] * b[1] + a[3] if f1 == 0: b[1] = b[0] break if f2 == 0: b[0] = b[1] break if f1 * f2 < 0: ans = (b[0] + b[1]) / 2 f3 = a[0] * pow(ans, 3) + a[1] * pow(ans, 2) + a[2] * ans + a[3] if f3 == 0: break elif (f3 < 0 and f1 < 0) or (f3 > 0 and f1 > 0): b[0] = ans elif (f3 < 0 and f2 < 0) or (f3 > 0 and f2 > 0): b[1] = ans ans = (b[0] + b[1]) / 2 print("%.2f" % ans) # 方法2 a3, a2, a1, a0 = map(float, input().split()) a, b = map(float, input().split()) def f(x): res = a3 * x ** 3 + a2 * x ** 2 + a1 * x + a0 return res # 区间端点是根 if f(a) == 0: ans = a elif f(b) == 0: ans = b else: # 判断f(a)f(b)的符号 while b - a >= 0.01: if f((a + b) / 2) == 0: ans = (a + b) / 2 break elif f((a + b) / 2) * f(a) > 0: a = (a + b) / 2 else: b = (a + b) / 2 else: ans = (a + b) / 2 print("%.2f" % ans)
7-15 天梯赛座位分配
N = int(input()) # 参赛的高校数 N （不超过100的正整数） a = [int(i) for i in input().split()] # 第二行给出 N 个不超过10的正整数，其中第 i 个数对应第 i 所高校的参赛队伍数 b = sorted(a) # 将队伍数量由小到大排列 for i in range(N): if N == 1: print('#1') start = 1 for i in range(a[0]): print(*range(start, start + 19, 2)) start += 20 break d_id = i + 1 x = N num = 0 finishSchoolNum = 0 d1 = a[:i] d2 = a[i + 1:] jud = 0 print('#{}'.format(d_id)) for j in range(1, a[i] + 1): if j > b[finishSchoolNum]: if b[finishSchoolNum] in d1: d_id -= d1.count(b[finishSchoolNum]) x -= b.count(b[finishSchoolNum]) finishSchoolNum += b.count(b[finishSchoolNum]) if x == 1: x = 2 if b[-2] not in d2: jud = 1 print(*range(num + d_id + jud, num + d_id + jud + x * 9 + 1, x)) num += x * 10
7-16 统计一批学生的平均成绩与不及格人数
grade = list(map(int, input().split(" "))) people = 0 sum = 0 n = 0 for i in grade: if i < 0: break n += 1 sum += i if i < 60: people += 1 if n > 0: average = "%.2f" % (sum / n) print('Average =', average) print('Count =', people) else: print("Average = 0.00")
