Add solution #2151

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,779 LeetCode solutions in JavaScript
+# 1,780 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1648,6 +1648,7 @@
 2148|[Count Elements With Strictly Smaller and Greater Elements](./solutions/2148-count-elements-with-strictly-smaller-and-greater-elements.js)|Easy|
 2149|[Rearrange Array Elements by Sign](./solutions/2149-rearrange-array-elements-by-sign.js)|Medium|
 2150|[Find All Lonely Numbers in the Array](./solutions/2150-find-all-lonely-numbers-in-the-array.js)|Medium|
+2151|[Maximum Good People Based on Statements](./solutions/2151-maximum-good-people-based-on-statements.js)|Hard|
 2154|[Keep Multiplying Found Values by Two](./solutions/2154-keep-multiplying-found-values-by-two.js)|Easy|
 2161|[Partition Array According to Given Pivot](./solutions/2161-partition-array-according-to-given-pivot.js)|Medium|
 2176|[Count Equal and Divisible Pairs in an Array](./solutions/2176-count-equal-and-divisible-pairs-in-an-array.js)|Easy|

solutions/2151-maximum-good-people-based-on-statements.js

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+/**
+ * 2151. Maximum Good People Based on Statements
+ * https://leetcode.com/problems/maximum-good-people-based-on-statements/
+ * Difficulty: Hard
+ *
+ * There are two types of persons:
+ * - The good person: The person who always tells the truth.
+ * - The bad person: The person who might tell the truth and might lie.
+ *
+ * You are given a 0-indexed 2D integer array statements of size n x n that represents the
+ * statements made by n people about each other. More specifically, statements[i][j] could
+ * be one of the following:
+ * - 0 which represents a statement made by person i that person j is a bad person.
+ * - 1 which represents a statement made by person i that person j is a good person.
+ * - 2 represents that no statement is made by person i about person j.
+ *
+ * Additionally, no person ever makes a statement about themselves. Formally, we have that
+ * statements[i][i] = 2 for all 0 <= i < n.
+ *
+ * Return the maximum number of people who can be good based on the statements made by the
+ * n people.
+ */
+
+/**
+ * @param {number[][]} statements
+ * @return {number}
+ */
+var maximumGood = function(statements) {
+  const n = statements.length;
+  let result = 0;
+
+  backtrack(0, new Array(n).fill(false), 0);
+  return result;
+
+  function isValid(goodPeople) {
+    for (let i = 0; i < n; i++) {
+      if (!goodPeople[i]) continue;
+      for (let j = 0; j < n; j++) {
+        if (statements[i][j] === 0 && goodPeople[j]) return false;
+        if (statements[i][j] === 1 && !goodPeople[j]) return false;
+      }
+    }
+    return true;
+  }
+
+  function backtrack(index, goodPeople, goodCount) {
+    if (index === n) {
+      if (isValid(goodPeople)) {
+        result = Math.max(result, goodCount);
+      }
+      return;
+    }
+
+    goodPeople[index] = true;
+    backtrack(index + 1, goodPeople, goodCount + 1);
+    goodPeople[index] = false;
+    backtrack(index + 1, goodPeople, goodCount);
+  }
+};