python数组拆分_面试题：用Python将一个数组分割成两个数组，使两个数组各自的和的差值最小...
输入一个任意长度的整形数组，输出两个数组，使得这两个数组各自的和最接近。如果有多个解决方案，返回任意一个就行 [1,2,3,4,5] -> [1,2,5] & [3,4] [1,2,3,4,10] -> [1,2,3,4] & [10] [1,1,1,-1,-1,-1] -> [1,1,-1,-1] & [1,-1] 或者 [1,1,1,-1,-1,-1] & []。
解法1：多项式
# Hello World program in Python
# coding=utf-8
import random
def test_input():
arr = [-3000]
for i in range(1000):
n = random.randint(-10, 20)
if n < 0:
n -= 100
elif n > 0:
n += 100
else:
continue
arr.append(n)
return arr
arr = test_input()
# 求和
def sum(a):
s = 0
for i in a:
s += i
return s
# 分离数组
def split_array(arr):
# 获取数组并排序
a = list(arr)
#a.sort()
# 另一个数组
b = list()
# 以上a,b作为待返回的数组
# 计算数组大小
n = len(a)#1000
#求和
smr = sum(a)
# 和的一半,简称半和
hs = smr / 2
# 临时和
s = 0
# 从最大的数字开始遍历数组
for i in range(-1,0-n,-1):
# 预判该数字加和结果
ns = s + a[i]
if ns > hs:
# 如果超出半和则跳过
continue
else:
# 如果未超过半和,则:
# 1, 取该元素加和
s += a[i]
# 2, 从 a 中将元素转移到 b
b.append(a[i])
a.pop(i)
# 如果最终和与半和之差,不够最小元素,则完成
if abs(s - hs) <= a[-1]:
break
return a, b
if __name__ == '__main__':
# 测试:
# [1,2,3,4,5] -> [1,2,5] & [3,4]
# arr = test_input()
print(split_array(arr))
解法2：背包问题
# Hello World program in Python
# coding=utf-8
import random
import copy
def test_input():
arr = [-300]
for i in range(100):
n = random.randint(-10, 20)
if n < 0:
n -= 100
elif n > 0:
n += 100
else:
continue
arr.append(n)
return arr
arr = test_input()
def incomplete_solution(arr):
total = sum(arr)
half = total / 2
print(total, half)
possibleSolution = {0: []}
for i in arr:
possibleSum = possibleSolution.keys()
for k in possibleSum:
now = i + k
if (now not in possibleSum):
valueList = possibleSolution[k]
nowList = copy.copy(valueList)
nowList.append(i)
possibleSolution[now] = nowList
if (now == half):
print("exactly match")
# print(nowList)
return nowList
# now we can not found a perfect solution, so here to find the closest
print(len(possibleSolution.keys()))
# TODO... find the closest solution
possibleSolution = {0: []}
for i in arr:
possibleSum = possibleSolution.keys()
for k in possibleSum:
now = i + k
if (now not in possibleSum):
valueList = possibleSolution[k]
nowList = copy.copy(valueList)
nowList.append(i)
possibleSolution[now] = nowList
if (now > half):
print("exactly match")
return nowList
if __name__ == '__main__':
#arr = [1, 2, 3, 4, 233, 12, 123] # test_input()
n = incomplete_solution(arr)
for i in n:
arr.remove(i)
print(n)
print(sum(n))
print(arr)
print(sum(arr))