RefStrSort.py

'''
you have an input string like "banana"
you want to sort the characters in the string
based on the order they appear in a reference string, 
e.g., "bna" so "banana" would sort as "bnnaaa"
'''

def solver(ref_str,str1):
 str_list = []
 for ref_char in ref_str:
 count = 0
 for char in str1:
 if char == ref_char:
 count += 1
 for i in range(count):
 str_list.append(ref_char)
 return ''.join(str_list) 

def solver1(ref_str,st1):
 str_list = []
 map = {}
 for char in str1:
 map[char] = map.get(char, 0) + 1
 for ref_char in ref_str:
 str_list.append(ref_char * map[ref_char])
 return ''.join(str_list)

str1 = 'banana'
ref_str = 'bna'

print solver1(ref_str,str1)