299. Bulls and Cows - LeetCode

Question

299. Bulls and Cows

Solution

題目大意:有一串隱藏的號碼,另外一我的會猜一串號碼(數目相同),若是號碼數字與位置都對了,給一個bull,數字對但位置不對給一個cow,注:數字對與位置對優先,一個號碼不能重複判斷.

思路:構造map結構,遍歷實現

Java實現:實現的不漂亮,好歹能經過

public String getHint(String secret, String guess) {
    Map<Character, Index> map = new HashMap<>();
    for (int i=0; i<secret.length(); i++) {
        Index idx = map.get(secret.charAt(i));
        if (idx == null) {
            idx = new Index();
            map.put(secret.charAt(i), idx);
        }
        idx.add(i);
    }

    int bulls = 0;
    int cows = 0;
    List<Character> cowsList = new ArrayList<>(); // for count cows
    // count bulls
    for (int i=0; i<guess.length(); i++) {
        Index idx = map.get(guess.charAt(i));
        if (idx != null) { // check digits
            if (idx.isBull(i)) {
                bulls++;
            } else {
                cowsList.add(guess.charAt(i));
            }
        }
    }
    // count cows
    for (char c : cowsList) {
        Index idx = map.get(c);
        if (idx.isCow()) {
            cows++;
        }
    }
    return bulls + "A" + cows + "B";
}

class Index {
    List<Integer> idxList;
    int count;

    // constructor
    public Index() {
        idxList = new ArrayList<>();
        count = 0;
    }

    void add(int x) {
        idxList.add(x);
        count++;
    }

    boolean isCow() {
        return count-- > 0;
    }

    boolean isBull(int x) {
        for (int tmp : idxList) {
            if (x == tmp) {
                count--;
                return true;
            }
        }
        return false;
    }
}

Ref

https://leetcode.com/problems/bulls-and-cows/discuss/74621/One-pass-Java-solution

public String getHint(String secret, String guess) {
    int bulls = 0;
    int cows = 0;
    int[] numbers = new int[10];
    for (int i = 0; i<secret.length(); i++) {
        int s = Character.getNumericValue(secret.charAt(i));
        int g = Character.getNumericValue(guess.charAt(i));
        if (s == g) bulls++;
        else {
            if (numbers[s] < 0) cows++;
            if (numbers[g] > 0) cows++;
            numbers[s] ++;
            numbers[g] --;
        }
    }
    return bulls + "A" + cows + "B";
}

public String getHint(String secret, String guess) {
    int bulls = 0;
    int cows = 0;
    int[] numbers = new int[10];
    for (int i = 0; i<secret.length(); i++) {
        if (secret.charAt(i) == guess.charAt(i)) bulls++;
        else {
            if (numbers[secret.charAt(i)-'0']++ < 0) cows++;
            if (numbers[guess.charAt(i)-'0']-- > 0) cows++;
        }
    }
    return bulls + "A" + cows + "B";
}