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114 lines
3.3 KiB
Markdown
114 lines
3.3 KiB
Markdown
# [299. Bulls and Cows](https://leetcode.com/problems/bulls-and-cows/)
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## 题目
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You are playing the Bulls and Cows game with your friend.
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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:
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The number of "bulls", which are digits in the guess that are in the correct position.
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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.
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Given the secret number secret and your friend's guess guess, return the hint for your friend's guess.
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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.
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**Example 1:**
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```
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Input: secret = "1807", guess = "7810"
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Output: "1A3B"
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Explanation: Bulls are connected with a '|' and cows are underlined:
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"1807"
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"7810"
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```
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**Example 2:**
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```
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Input: secret = "1123", guess = "0111"
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Output: "1A1B"
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Explanation: Bulls are connected with a '|' and cows are underlined:
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"1123" "1123"
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| or |
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"0111" "0111"
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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.
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```
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**Example 3:**
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```
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Input: secret = "1", guess = "0"
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Output: "0A0B"
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```
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**Example 4:**
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```
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Input: secret = "1", guess = "1"
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Output: "1A0B"
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```
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**Constraints:**
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- 1 <= secret.length, guess.length <= 1000
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- secret.length == guess.length
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- secret and guess consist of digits only.
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## 题目大意
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你在和朋友一起玩 猜数字（Bulls and Cows）游戏，该游戏规则如下：
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写出一个秘密数字，并请朋友猜这个数字是多少。朋友每猜测一次，你就会给他一个包含下述信息的提示：
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猜测数字中有多少位属于数字和确切位置都猜对了（称为 "Bulls", 公牛），
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有多少位属于数字猜对了但是位置不对（称为 "Cows", 奶牛）。也就是说，这次猜测中有多少位非公牛数字可以通过重新排列转换成公牛数字。
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给你一个秘密数字secret 和朋友猜测的数字guess ，请你返回对朋友这次猜测的提示。
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提示的格式为 "xAyB" ，x 是公牛个数， y 是奶牛个数，A 表示公牛，B表示奶牛。
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请注意秘密数字和朋友猜测的数字都可能含有重复数字。
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## 解题思路
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- 计算下标一致并且对应下标的元素一致的个数，即 x
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- secret 和 guess 分别去除 x 个公牛的元素,剩下 secret 和 guess 求共同的元素个数就是 y
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- 把 x， y 转换成字符串，分别与 "A" 和 "B" 进行拼接返回结果
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## 代码
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```go
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package leetcode
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import "strconv"
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func getHint(secret string, guess string) string {
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cntA, cntB := 0, 0
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mpS := make(map[byte]int)
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var strG []byte
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n := len(secret)
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var ans string
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for i := 0; i < n; i++ {
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if secret[i] == guess[i] {
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cntA++
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} else {
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mpS[secret[i]] += 1
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strG = append(strG, guess[i])
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}
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}
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for _, v := range strG {
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if _, ok := mpS[v]; ok {
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if mpS[v] > 1 {
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mpS[v] -= 1
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} else {
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delete(mpS, v)
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}
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cntB++
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}
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}
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ans += strconv.Itoa(cntA) + "A" + strconv.Itoa(cntB) + "B"
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return ans
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}
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``` |