bulls-and-cows (#96)

string/bulls-and-cows.js

@@ -0,0 +1,92 @@
+/**
+299. Bulls and Cows
+
+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.
+*/
+
+/**
+ * @param {string} secret
+ * @param {string} guess
+ * @return {string}
+ */
+var getHint = function (secret, guess) {
+  const map = {};
+
+  for (let i = 0; i < secret.length; i++) {
+    const char = secret[i];
+
+    if (char in map) {
+      map[char][i] = i;
+    } else {
+      map[char] = { [i]: i };
+    }
+  }
+
+  const checkedIndicies = {};
+  let bulls = 0;
+  let cows = 0;
+  for (let i = 0; i < guess.length; i++) {
+    const char = guess[i];
+
+    if (char in map && i in map[char]) {
+      bulls++;
+      checkedIndicies[i] = i;
+
+      delete map[char][i];
+
+      const isEmpty = Object.keys(map[char]).length === 0;
+      if (isEmpty) {
+        delete map[char];
+      }
+    }
+  }
+
+  for (let i = 0; i < guess.length; i++) {
+    const char = guess[i];
+
+    if (!(i in checkedIndicies) && char in map) {
+      cows++;
+
+      const firstKey = Object.keys(map[char]).at(0);
+
+      delete map[char][firstKey];
+
+      const isEmpty = Object.keys(map[char]).length === 0;
+      if (isEmpty) {
+        delete map[char];
+      }
+    }
+  }
+
+  return `${bulls}A${cows}B`;
+};