299. Number guessing game

• Question no ： Power button 299
• Knowledge point ： Hashtable , character string , Count
• Goal completion ：23/150
• summary
  stem ：
  
  

Ideas ：

• 1. General idea ： Look for the ‘ Bull ’, Then delete the bull and find ‘ cow ’.
• 2. Concrete realization ：
  • （1） Put two strings into the dictionary , Build hash table .
  • （2） First traversal , lookup ‘ Bull ’, That is, elements with the same index position and characters , When found, the... In the two hash tables will be value reduce 1, This step is a bit like Xiaole ？
  • （3） Second traversal , lookup ‘ cow ’（ In the last step, the bull has been eliminated ）, If the element j Exists in both hash tables and value>0, It means it's a cow

class Solution:
    def getHint(self, secret: str, guess: str) -> str:
        hashmap = {
    }
        hashmap2 = {
    }
        ret = [0, 0]
        for s in secret:
            if s in hashmap:
                hashmap[s] += 1
            else:
                hashmap[s] = 1
        for g in guess:
            if g in hashmap2:
                hashmap2[g] += 1
            else:
                hashmap2[g] = 1
        for i in range(len(guess)):
            if guess[i] == secret[i]:
                ret[0] += 1
                hashmap[guess[i]] -= 1
                hashmap2[guess[i]] -= 1
        for j in guess:
            if hashmap2[j] > 0:
                if j in hashmap:
                    if hashmap[j] > 0:
                        ret[1] += 1
                        hashmap[j] -= 1
                        hashmap2[j] -= 1
        ans = str(ret[0]) + 'A' + str(ret[1]) + 'B'
        return ans

• Reference resources ： The simpler way to solve the problem