Python程序获取字符串构造的最少元素

给定一个字符串，任务是编写一个Python程序来计算从列表元素形成字符串所需的最少元素。

Input : test_list = [“geek”, “ring”, “sfor”, “ok”, “woke”], tar_str = “working” 
Output : 2 
Explanation : working can be formed using woke and ring.

Input : test_list = [“geek”, “ring”, “sfor”, “ok”, “woke”], tar_str = “workinggeek” 
Output : 3 
Explanation : workinggeek can be formed using woke, geek and ring. 
 

方法：使用 issubset() + set() +组合()

在这里，我们迭代一个字符串列表并形成所有大小的组合，每个组合都被转换为 set 并使用 issubset() 检查是否形成目标字符串，如果找到，则退出循环并记录计数。

Python3

# Python3 code to demonstrate working of 
# Minimum elements for String construction
# Using issubset() + set() + combinations()
from itertools import combinations
  
# initializing list
test_list = ["geek", "ring", "sfor", "ok", "woke"]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing target string 
tar_str = "working"
  
res = -1
set_str = set(tar_str)
done = False
for val in range(0, len(test_list) + 1):
      
    # creating combinations
    for sub in combinations(test_list, val):
          
        # contructing sets of each combinations 
        temp_set = set(ele for subl in sub for ele in subl)
          
        # checking if target string has created set as subset
        if set_str.issubset(temp_set):
            res = val
            done = True
            break
    if done:
        break
  
# printing result 
print("The Minimum count elements for string : " + str(res))

输出：

The original list is : ['geek', 'ring', 'sfor', 'ok', 'woke']
The Minimum count elements for string : 2