299 Bulls and Cows

299 Bulls and Cows

Comment 

https://leetcode.com/problems/bulls-and-cows/

First my solution is to loop it for once to get the dict of the secret. Then loop it for a second time.

Then I see that it can be done in one loop.

version2.py

class Solution(object):
    def getHint(self, secret, guess):
        """
        :type secret: str
        :type guess: str
        :rtype: str
                """
        d = {}
        bull, cow = 0,0

        for index,s in enumerate(secret):
            if guess[index] == s:
                bull += 1
            else:
                d[s] = d.get(s,0) + 1

        for index,s in enumerate(secret):
            if (guess[index] != s) & (d.get(guess[index],0) != 0):
        	    cow += 1
        	    d[guess[index]] -= 1
        	    
        return str(bull) + "A" + str(cow) + "B"       

version3.py

class Solution(object):
    def getHint(self, secret, guess):
        """
        :type secret: str
        :type guess: str
        :rtype: str
                """
        ds = {}
        dg = {}
        bull, cow = 0,0

        for index,s in enumerate(secret):
            if guess[index] == s:
                bull += 1
            else:
                if ds.get(guess[index],0) == 0:
                    dg[guess[index]] = dg.get(guess[index],0) + 1
                if dg.get(s,0) == 0:
                    ds[s] = ds.get(s,0) + 1

                if ds.get(guess[index],0) != 0:
                    ds[guess[index]] = ds.get(guess[index],0) - 1 
                    cow += 1
                if dg.get(s,0) != 0:
                    cow += 1
                    dg[s] = dg.get(s,0) - 1
         
        return str(bull) + "A" + str(cow) + "B"