# 299. Bulls and Cows

Medium
You are playing the Bulls and Cows game with your friend.
You write down a secret number and ask your friend to guess what the number is. When your friend makes a guess, you provide a hint with the following info:
• The number of "bulls", which are digits in the guess that are in the correct position.
• The number of "cows", which are digits in the guess that are in your secret number but are located in the wrong position. Specifically, the non-bull digits in the guess that could be rearranged such that they become bulls.
Given the secret number `secret` and your friend's guess `guess`, return the hint for your friend's guess.
The hint should be formatted as `"xAyB"`, where `x` is the number of bulls and `y` is the number of cows. Note that both `secret` and `guess` may contain duplicate digits.
Example 1:
Input: secret = "1807", guess = "7810"
Output:
"1A3B"
Explanation:
Bulls are connected with a '|' and cows are underlined:
"1807"
|
"7810"
Example 2:
Input: secret = "1123", guess = "0111"
Output:
"1A1B"
Explanation:
Bulls are connected with a '|' and cows are underlined:
"1123" "1123"
| or |
"0111" "0111"
Note that only one of the two unmatched 1s is counted as a cow since the non-bull digits can only be rearranged to allow one 1 to be a bull.
Constraints:
• `1 <= secret.length, guess.length <= 1000`
• `secret.length == guess.length`
• `secret` and `guess` consist of digits only.

### 解題

func getHint(secret string, guess string) string {
m := make(map[byte]int)
a := 0
b := 0
for i := 0; i < len(secret); i++ {
if secret[i] == guess[i] {
a++
} else {
m[secret[i]]++
}
}
for i := 0; i < len(guess); i++ {
if secret[i] != guess[i] {
if m[guess[i]] > 0 {
b++
m[guess[i]]--
}
}
}
return strconv.Itoa(a) + "A" + strconv.Itoa(b) + "B"
}